List of Super Mario Bros. glitches
Brick Block Glitch
In World 6-3, the player must wait on a mushroom. If playing the NES or SNES version, after a while one of the Bullet Bills, if jumped on, will fall on a string, like a Pulley Lift, although it will fall much slower. Occasionally, it will even stay suspended in the air. Please note that, due to the long time spent waiting for the strange Bullet Bill, Mario's/Luigi's timer will go off, costing him a life.
Die and Complete Simultaneously
While going to any castle level, Mario or Luigi should go through the whole level by becoming Small Mario or Luigi. Mario or Luigi will need to touch the axe as usual, but if Bowser touches Mario or Luigi while he touches the axe, he will die and complete the level. If Mario or Luigi does it with 0 lives, he will die and win, but then after the text that says "Thank you Mario! But our princess in another castle!" is over, the Game Over screen will be shown.
Super Mario Bros. was not programmed to have two Power-Ups on the screen at the same time. Thus, if a Power-Up comes out of its block and is not used, and a second one then comes out of its block, the first Power-Up will disappear from the screen at the moment the second one comes out. This was not fixed in Super Mario All-Stars. This is actually very useful in the game's sequel, because in the game's coding, Poison Mushrooms are considered a Power-Up, and therefore finding a second Power-Up will cause the Poison Mushroom to disappear.
Sometimes, if someone breaks the bricks at the end of World 3-1 at just the right place, the trampoline will disappear. If Mario lands where the trampoline used to be, he will not be able to move until the time runs out or the game is reset.
To perform the Double Death glitch, the player must be on any level with a Hammer Brother. The player must allow themselves to die by hitting its hammers. When Mario dies, the player must pause the game, then unpause. He or she may need to do this once more, while the death music is playing. If done correctly, when a second hammer reaches the area Mario was at, the death music will repeat. It's also possible to perform it without pausing by falling into a pit then with a hammer reaching the area Mario was at.
This glitch was found nearly 30 years after the game came out. The player has to beat the game and restarting in Hard Mode with two players. Mario must die in World 1-2, while Luigi must go to World 5-2, hit a block with a Vine, hold it, and get killed by a Hammer Brother nearby. If done correctly, after Mario enters in the pipe for World 1-2, a Vine suddenly pops out from the ground. Mario can even do an infinite 1 up trick by holding the vine and waiting for the nearby Buzzy Beetles.
This is because the game thinks the player is going to Coin Heaven where the vine would appear from the ground when dying.
A similar glitch exists where the player gets hit by the Hammer Brother in World 5-2 while on a vine. Doing so will result in an invisible vine near the start of the level when the player respawns.
Due to the graphical limitations of the NES, sometimes the defeat of one enemy meant the spawning or the disappearance of another. This is also notable in Super Mario Bros.: The Lost Levels. However, this glitch has been fixed in Super Mario All-Stars and Super Mario Bros. Deluxe.
Through incredibly precise movements, the player must jump right next to the block that holds the flagpole and then jump again. If done correctly, Mario or Luigi will jump onto the flagpole normally, but the flag will remain raised.
Floating Buzzy Beetle
To do this glitch, the player must replay World 1-1 in hard mode. Then he or she must go to the left side of the second pit. Mario must wait until one of the Buzzy Beetles is about to fall into the pit, and once one does Mario must jump on top of one while it falls into the pit, then bounce out of it to the other side. If done correctly the Buzzy Beetle's shell will stop in midair. When it comes out of the shell it will be walking in midair and can float through walls.
Passing Through Enemies without Getting Hurt
The NES has poor collision detection, making it possible to touch the outside pixels of an enemy without getting hurt if enough speed is gained through dashing.
To perform the Hands Up glitch, Mario must reach a flagpole after collecting a Fire Flower. He must throw a Fireball the instant he touches the flagpole. If done correctly, when he walks to the castle, his arms will be raised as if he was still going down the flagpole.
For the Harmless Enemy glitch to work, Mario or Luigi must be either Super Mario or Fire Mario. He must take damage from an enemy of any kind. If he stays where the enemy is, he won't take any more damage. If he stops touching the enemy and then tries touching it again, he will take damage. This bug remained in the All-Stars release but was fixed in the Deluxe version.
Hit the Axe and Keep It There
In any of the castle levels, the player must go to Bowser or False Bowser and defeat him with fireballs. Then, Mario must run and jump so he will touch the far right side of the axe. The screen will scroll to the mushroom retainer but the axe will still be there.
Instant Game Over
When the player gathers exactly 128 lives, then loses a life, they will receive an instant Game Over. This is most likely caused by a data overflow (signed byte), as the developers may not have thought said number of lives could be earned. (They may be acquired via "turtle-tipping," the infinite 1 up trick.) In the SNES remake, the life count will be simply capped at 128 instead.
Invisible Piranha Plant
In World 8-4, there is a short underwater section. In the pink pipe that the player enters at the beginning of this section, a Piranha Plant is there, but it is invisible. Despite it being invisible, the player can throw fireballs at it, as well as take damage from it. In Super Mario All-Stars, the glitch is fixed as the Piranha Plant can now be seen underwater.
Jumping Damage Glitch
In World 1-1, when the player gets to the Brick Blocks high above the ground close to a pitfall with two Goombas walking towards it, he or she must stand on the edge of the Brick Blocks and wait until the Goombas appear on the screen. Then, the player must back up and wait for the first Goomba to approach the pitfall. As soon as it's about to fall in, the player must start running to the edge and when he falls, he or she must jump high to the left. The player should go off-screen from the top. If done correctly, Mario or Luigi will die. If the player is Super Mario or Super Luigi or Fire Mario or Fire Luigi, he or she will simply shrink as if he or she has just been hit by an enemy. The timing for this glitch can be difficult.
Jumping in Midair
When the player gets a power-up (except for the Starman) in midair, and presses the button while Mario is transforming, he will jump in midair. If this happens with a Fire Flower, the fireball sound will replace Mario's jump sound. This can also be done in the SNES remake.
This glitch also works in World 1-1. In the part where the second mushroom block is in Mario's or Luigi's Small Form, then the player should get the mushroom off the bottom gap. As soon as this happens, the player must jump to the top of the level. If done correctly, the player will become their Super form, even though the Mushroom has fallen off the gap. This is because certain objects overlap to the top of the screen as they fall in a hole, only disappearing when the last pixel is down the hole. They can't be seen because Super Mario Bros. has no vertical scrolling.
The Minus World is one of the most infamous glitches in Super Mario Bros. and in video game history. It is an endless underwater level, identical to World 7-2, and once there, Mario or Luigi is doomed to the death from either running out of time or being killed by enemies. While there is no strategic advantage in performing this glitch, many find it intriguing. The glitch was removed in all remakes of the game, excluding the imports and Virtual Console remakes. The Japanese Disk System version of the game includes a different version of the Minus World (even though the game itself doesn't have other differences). It contains three levels that can be beaten, and once -3 is complete the player will return to the title screen as if they have beaten the game.
To perform the glitch, Mario must go to World 1-2 and stand on top of the pipe that leads to the above-ground flag, without going in the pipe. Then he must break the second and third block from the pipe, but leave the one on the far right. Then he must stand on the left edge of the pipe (facing left) and duck. He then has to jump while in a ducking position and move right in mid-air (while still facing left). If done correctly, Mario will go through the block on the far right and through the wall to the Warp Zone. Mario must then go through the pipe that would normally lead to World 4-1 (the one on the far left), and Mario will enter the Minus World (world -1; it's actually World 36-1, but the game displays the number 36 as a single blank space).
There is also a third way to activate that glitch. The player needs a Famicom, a Super Mario Bros. game cartridge, and a Tennis game cartridge. To activate the glitch, the player needs to start playing Super Mario Bros.. After a few seconds, slowly and carefully take the cartridge from the console and replace it with the Tennis game. After that, the player needs to reset the game. The player needs to play a match, and after a few seconds, do the same thing as with the Super Mario Bros. cartridge. When the title screen appears, the player is required to hold down and press , and the Minus World will generate. The Minus World will be different depending on score get during the match in Tennis.
If World 2-2 or 7-2 is edited in a ROM editor, so that it is possible to beat it during the underwater segment, there is a World -2, an underwater version of 3-4. If World 3-4 is edited in a ROM editor, then, there is a World -3. It is also a version of 3-4, but with overworld graphics.
Moonwalking Through Walls
On any level with a ceiling that has a hole in it, the player must scroll the screen to the left so half of Mario can fit there. Mario must go to the left side of the screen, jump, and not fall. Holding down left and repeatedly jumping will cause Mario to get inside of the wall, allowing the Mario Jackson glitch to occur, where Mario begins to moonwalk. Moonwalking is possible in NES and SNES versions.
This works in World 1-1. Mario or Luigi must hit the block with the Starman inside, then they must go to the bit with the half pyramid with 10 blocks on each half, without touching the Starman. Then they let the Starman touch them, and as quickly as possible, the player must run to the flagpole. If done correctly, when the invincibility wears off, the overworld music from the level will interrupt the part of the usual flagpole fanfare.
Over the Flagpole
On some levels, it is possible to jump over the flagpole. Beyond the flag pole is nothing but an endless path. There is nothing to do; all that can be done is wait for the timer to get to zero. To do this glitch in World 1-1, right after the second pit, Mario needs to wait for the Koopa Troopa to about to fall into the pit and simultaneously jump at the top of the level right above the Koopa. After that, the Koopa will be stuck underneath the level, but the player will still be able to see it. When the Koopa starts to walk under the level, Mario should follow it to the end. Along the way, it's required to grab a Super Mushroom. When the Koopa is halfway between the staircase and the flagpole, the player must do the glitch again and Mario will jump above the flagpole.
To do this glitch in World 3-3, at the end of the level the player must stand off the last lift until another one has completely lifted, before falling off. After that, the player must accelerate as fast as possible and jump from the far edge of the lift. The lift should not lower while doing so.
In Super Mario Bros.: The Lost Levels, this is actually exploited to hide Warp Zones. In worlds 3-1 and A-3, there are warp zones placed beyond the goals. In other worlds, while it is possible to go over the flagpole, the edge of the world is a few steps past the fortress, and the player is not able to go far enough that the flagpole is out of reach.
On a side note, this glitch was fixed in the SNES version of the game.
This glitch/trick was featured in the 25th-anniversary super play.
While the timer of the game will eventually cause Mario or Luigi to lose a life upon running out, if the player were to disable the timer using a cheat code and continuing running, they will eventually reach an area where the background and platform sprites become jumbled.
Path Puzzle Glitch
When there is a path puzzle where the player must choose the right path, if Mario is on the right one but jumps repeatedly, the game will think he's on the wrong path and will not allow him to continue the level (there will be the usual loop).
Red Shell Out of Thin Air
The Red Shell Out of Thin Air glitch can be performed in World 3-1. After avoiding three Koopa Paratroopas below the Brick Blocks with a Green Koopa, it's possible to make a Red Shell appear. First, the player should attack the Green Koopa from below the bricks. Then, when the Koopa is about to come out of its upside-down shell, the player should hit the bricks again. If it is done at the right time, the green shell will turn in to a red one. It can also happen in levels 4-1 and 6-1. At the ending, there are two Question Blocks. The player must make the Lakitu throw a Spiny Egg aiming above the blocks. If the player hits the block while an egg lands on it, it will still become a red shell.  This glitch wasn't fixed when Super Mario All-Stars was released.
Sliding on one foot
If Fire Mario jumps and shoots a fireball right when a level starts or he comes out of a pipe, he will not move his feet when he walks. This glitch wears off after a few seconds or if he gets hit.
Small Fire Mario
The small Fire Mario glitch is performed by having Super Mario, Fire Mario, Super Luigi, or Fire Luigi hit the axe. If Bowser hits the player while the player hits the axe, Mario will flash but stay Super Mario. Bowser will be defeated, and then the player will move on to the next level after rescuing the level's mushroom retainer. The game continues as normal, except when the player gets hit, they die. Collecting a Super Mushroom will make the player Small Mario, and when they get hit they'll become Super Mario again. When the player grabs a Fire Flower as Small Mario, the player will become Fire Mario, but in the smaller body. When Mario shoots a fireball, he will become large, then, when the animation is complete, he returns to the small size. If Mario dies, the player will need to repeat the glitch to play as him again. A similar variation on this is to do the same thing with Small Mario. Mario will do his usual dying animation, but the screen will scroll over, like normal, to the mushroom retainer, even though there is no Mario. When transforming, Mario will do a swimming "pose" on the ground.
Also, in the Japanese version of Super Mario Bros. Deluxe, the player can get small Fire Mario like this; When the player is Fire Mario and hits an enemy, the player must pause and click save, small Fire Mario will appear. However, Mario will lose a life in one hit, unlike small Fire Mario in Super Mario Bros. For the short sequence of Mario's death when he dies from a Time-Up, and when Mario has a Fire Flower, the player should notice that small Fire Mario is actually appearing instead of the normal dead Small Mario.
One of the challenges in NES Remix involves defeating 20 enemies with small Fire Mario.
At the end of swimming levels, there is one block-sized space above the Warp Pipe that leads to the exit. If the player crouches as Super Mario and then swims into space while still crouching, Mario should walk backward and get stuck in the far right side of the wall. After pulling off this glitch, it is impossible to move. This works in the NES version, but not in the Super Mario All-Stars version, as the space directly above the Warp Pipe has been filled up with a block. This also cannot be done in Super Mario Bros. Deluxe.
Thousand Seconds Left
In Super Mario Bros.: The Lost Levels, if the player clears a castle with the timer at "000", the game thinks that the player cleared with 1000 seconds left which will result in gaining 50000 points. This can be done for all castle levels and is a tactic some players use to do a high score playthrough. Doing this in all of the game's castles can give the player a total of 600,000 points. This works in both games in Super Mario All-Stars.
The player must press the button to jump and get a Super Mushroom. The player must not collect it but chase it and then collect it. Mario will not receive the power-up and the player cannot obtain the mushroom. If the player presses to jump on the mushroom, the mushroom will disappear. This glitch wasn't fixed in the All-Stars version or the Super Mario Bros. Deluxe version and the Virtual Console release.
If the player touches the vine at the extreme left edge of the screen, Mario or Luigi will be teleported to the right edge. The All-Stars version did not fix this.
Walking Through Walls
In any level with walls just above the ground, the player must scroll the screen far enough so half of Mario can fit in it. Then they must jump in it, holding left, and jumping rapidly. They will slide through the wall. In levels like castle levels, Mario can access the ceiling this way.
If Mario's foot catches on a wall or pipe, he can jump again to do the Wall Jump at that frame. However, Mario has to be moving toward the wall with some velocity. This is because when Mario hits a wall, he goes slightly into the wall. The bricks in the wall count as individual surfaces, so Mario has a surface to jump off. This glitch existed on Super Mario Bros. 3, Super Mario World and Yoshi's Island.
Sometimes an entry point like a vine or pipe teleports Mario somewhere else than its intended destination. This glitch occurs because the game can only determine one area as the destination where all pipes and vines on the current screen lead to. Usually, this information is updated before Mario can access the next pipe so that he gets teleported to the right area. However, if Mario leaves the center of the screen and gets further right than usual, which can be done with backward jumps or by wall clipping, he can get into a pipe before the teleport destination gets updated, so that said pipe leads to the area which should be entered through the previous entry point. On the other hand, if Mario runs far enough to update the teleport destination for an upcoming entry point, while another pipe is still visible on the left half of the screen and then runs back to enter the latter, this pipe leads to the updated destination. The Wrong Warp glitch is best known for being used in 4-2 and 8-4:
Getting Sucked into the Wall
In any level with walls at midair, the player must stand under the bottom corner of that wall, then jump while slightly tapping the same direction of the corner (e.g. if the player is standing under the bottom-right corner, then they have to tap right) for the first few frames of the jump, if done correctly, Mario will get sucked into the wall. The player can also jump rapidly while holding the same corner direction to get sucked in further and slide through further walls. They can also jump out of the wall by jumping without holding a direction after getting sucked into the wall to do a "standstill wall jump". Doing this under the bottom corner of a ? Block with a power-up on top of it can cause Mario to get powered up from underneath the block.