List of Super Mario World 2: Yoshi's Island glitches

This is a list of glitches in the game Super Mario World 2: Yoshi's Island.

Glitches
NOTE: All names are conjectural unless otherwise specified.

Bowser glitch
This glitch is hard to execute. When fighting the final boss, if Bowser gets close enough and breaks all the platforms, he flips and heads in reverse. He duplicates a lot of times, and returns later. This glitch has a somewhat extremely slow progression. Also, if all the platforms have been destroyed when Bowser is defeated, the game freezes due to Bowser not landing on a platform.

Eating Baby Mario
NOTE: Yoshi must have the 10 Stars or 20 Stars item to activate this glitch.

In World 5-5: Goonie Rides!, the player should go to the area with the helicopter bubble. The player should hit a Goonie and wait until the counter reaches zero. While the Toadies are taking Baby Mario away, the player should quickly hit him with Yoshi's tongue and touch the helicopter bubble. Once Purple Yoshi has already transformed, the Toadies try to take Baby Mario again. When they pop Baby Mario's bubble, the player must open their inventory and select the 10 Stars or 20 stars item. When the Toadies are gone, the player must wait until Yoshi transforms back to normal. Yoshi is able to eat Baby Mario if he grabs him with his tongue. Even though Baby Mario is still missing, the game does not freeze, but the level is rendered impossible to complete.

In World 2-7: Lakitu's Wall, the player can do the same glitch; after keeping Baby Mario in Yoshi's mouth, he must hit the Message Block to cause Baby Mario to reappear in the air. After doing this two or three times, he should be able to hop back on Yoshi's back; however, his sprite animation while moving Yoshi becomes unstable. The player can fix this by popping a car bubble.

In Yoshi's Island: Super Mario Advance 3, the Toadies will ignore Baby Mario while he is in his bubble if attempting this glitch.

Glitchy screen
NOTE: This glitch occurs on the console and not the game, and is not present on all SNES consoles.

This glitch occurs during specific areas where the graphics are rendered incorrectly. It seems to occur where translucent and transparent objects are. The screen becomes filled with various twitching objects, and Yoshi as well as all other enemies and objects disappear. Since the player cannot see anything but the terrain, this glitch makes the game nigh unplayable. The screen momentarily returns to normal when the game is paused, although it is only visible for a fraction of a second. This glitch appears to be a flaw in the SNES's rendering capabilities as opposed to the game's, as it only occurs on specific consoles and not specific cartridges.

Giant Egg in other stages
Giant Eggs cannot be carried into other stages as soon the player passes by the goal roulette; however, this can be bypassed by going into one of the stages that can make Giant Eggs (for example, World 2-7). At the end of the level, Yoshi must go to the far right of the goal roulette, jump and throw a Giant Egg in the air. As soon as the Giant Egg lands, Yoshi must tongue-grab the egg and it should stand on the ground. Next, Yoshi must jump into the goal roulette, and the next Yoshi should be able to pickup the egg and carry it into another level. Like the Huffin Puffin chicks, the egg becomes glitchy but can still function correctly.

In Yoshi's Island: Super Mario Advance 3, Yoshi can no longer tongue-grab the Giant Egg, making it impossible to perform this glitch.

No Auto-scroll in Poochy Ain't Stupid
At the start of World 1-Extra, Poochy Ain't Stupid, Yoshi will encounter some Fang enemies continuously being spawned. Without advancing too far to the right (thus causing the auto-scroll to begin and cancel out this glitch), the player has to jump on the Fangs until Yoshi is off-screen. From there, they have to Flutter Jump to the right and land on the high floor. If Yoshi drops down, he will be able to play the rest of the level without the screen automatically scrolling. However, if the player goes too far to the left after dropping down from the high floor, the level will begin auto-scrolling, and the screen will not be able to scroll manually again without clearing or exiting the level, or losing a life.

Null egg
The "null egg" is an invisible egg that can crash the game, and performing this glitch is very precise. To begin the glitch, the player needs to carry six eggs and eat the Little Skull Mouser, and jump as soon as the Little Mouser holding the egg falls to hopefully trigger the null egg. Next, Yoshi should go up to the hill and pan the camera upwards to reveal another Little Skull Mouser, and fire two eggs and make Yoshi go to the end of the stage. As the player does so, if Yoshi still has the Little Skull Mouser and spit it out as soon as Yoshi is near the goal and then jump into the goal roulette the glitch is performed successfully. Failure to do the glitch without despawning some sprites can crash the game as the player touches the goal roulette. The Little Skull Mouser has an ID of 10, which is the same as the null egg; the player can get rid of the glitched Little Skull Mouser so another sprite can take its place.

The null egg can do various amounts of glitches depending if the ID number is 10:
 * Loads flowers from each exit room.
 * Load exit sprites: Plays a screen exit and upon entering an exit sprite. This can warp Yoshi to World 1-1.
 * Using the world key: After the player defeats the castle boss without throwing the null egg, the key will appear and is stored to the null egg. This causes a cutscene to play automatically each time the player enters a level; this will go as far as the screen goes and all the sprites will pass by Yoshi as he goes forward; however, some levels where a Ukiki captures Baby Mario can still kidnap him. This will work on any level except World 6-8 and causes the cutscene to be unplayable.
 * Carry a goal ring: The player needs to have some real eggs, a null egg, and a key. At the end of World 2-1, Yoshi should enter the minigame Popping Balloons and win the game. The player should have at least one balloon and then collect the prize. As soon as Yoshi exits the minigame, the Little Skull Mouser will damage him. Yoshi must flutter to the left to load three falling platforms, then fire off some eggs and the null egg at the goal roulette and it will stop. The player can now pick up the goal roulette and carry it around the stage.

Message Block's hidden power
In World 2-7, Lakitu's Wall, Yoshi can eat a Fat Guy for a Giant Egg. When Yoshi arrives to the part with a car bubble, he should hit the Message Block with the Giant Egg to make every thing freeze for a little while. When that is over, the stars from above will fall to the ground and Yoshi becomes invisible. Yoshi can still walk around while unseen. If Yoshi jumps through the goal roulette while invisible, the whole game freezes and the player must reset their Super Nintendo Entertainment System. In the Japanese version, the controller becomes unresponsive after the Message Block text appears, requiring a reset.

In Yoshi's Island: Super Mario Advance 3, hitting the Message Block with an Egg or Giant Egg goes through them, making it impossible to perform this glitch.

Nothing in Yoshi's mouth
In places like World 3-1, there may be situations where it looks like Yoshi has something in his mouth, but he really does not. First, the player must have Yoshi eat a Grinder and keep it in his mouth until he reaches the Middle Ring. Then, as soon as the player touches the ring, he must spit the Grinder out (the player must hold up while spitting it out). The Grinder that Yoshi spits out turns into a star, but before it even does that, the player can see that the spat out Grinder is invisible. When the checkpoint sequence ends, the star from the Grinder can be collected, but Yoshi also has an invisible object in his mouth. He can still stick his tongue out, but he cannot eat enemies. When the player presses down with the invisible object still in Yoshi's mouth, he produces an invisible egg.

This glitch can also be performed in World 3-3. The player can either use a Giant Egg or a POW Block power-up. After performing the glitch correctly, the player can use Yoshi's glitched state to break the game, reach the Stretch and defeat the small green Shy Guy, then turn and hold left and take damage with Yoshi's tongue sticking out. He will turn invisible, and once he does grab Baby Mario and start fluttering to the right, he must reach the morph bubble before the game crashes. This causes the stage to become unstable (though this can be fixed by touching a Middle Ring and purposely losing a life), and failing to grab the morph bubble crashes the game. By touching the bubble, this can prevent the game from crashing and function somewhat normally. As the result of using the glitch, after beating the World 3 boss Naval Piranha, the cutscenes throughout the rest of the game (including the ending cutscene) are broken, and all of the sprites on Yoshi's Island are placed at random locations as the cutscene plays out.

Warp glitch
This glitch is possible in the SNES version. There are several levels where this glitch can be performed, and all of them rely on Yoshi entering a warp from multiple coordinates. In the Game Boy Advance version, Yoshi's Island: Super Mario Advance 3, it causes the game to freeze.

In 1-4: Burt The Bashful's Fort, Yellow Yoshi must go into the second room where the locked door is located and enter the pipe. He must then face right and aim an egg shot, wait for a moment, and hop backwards to be damaged by a Piro Dangle. Once Baby Mario is floating and just about near Yoshi, he should keep fluttering up to the exit until he grabs him. This causes Yoshi warp out of the fortress and skip the miniboss.

In 2-4: Bigger Boo's Fort, before Yellow Yoshi leaves the second section through the Warp Pipe, the player must let the lower Boo Blah go towards Yoshi and the pipe. When the Boo Blah meets the pipe, Yoshi must jump on it and enter the Warp Pipe at the same time. That way, Yellow Yoshi enters the pipe, but overhead. This causes the game to warp Yoshi out of the fortress and skip the miniboss.

In 3-1: Welcome To Monkey World!, when Green Yoshi meets the secret passage to the bonus area, he must simply jump in the water on the left overhead wall and dive in towards the left. Then, the player must press Pause before doing it, making sure to go towards the left and then quickly get back to the warp. If done correctly, Yoshi is warped out of the level.

In 4-7: Ride Like The Wind, Red Yoshi must have used the hidden spring ball towards the platform before the bonus area. Before Red Yoshi enters the bonus area, he must spring off the spring ball and touch the left wall at the same time. If done right, Red Yoshi touches the left wall and be warped out of the stage. Yoshi can also bring Huffin Puffin chicks into World 1-1; however, if they are taken to another stage, their sprite becomes glitchy and turns into a red version of the tile used for Arrow Clouds, though they still function correctly.

In 5-4: Sluggy The Unshaven's Fort, Yellow Yoshi must grab a Shy Guy in his mouth with some eggs with him. Once he reaches the pipe, he should get rid of the thorns on the floor to reveal a pit. Yellow Yoshi must then stand to the left of the pipe and spit out the Shy Guy so it can land on the floor, then step on it and fall to the pit. As soon as Yoshi is off-screen, he should flutter to the left and trigger the exit. This glitch is very difficult and precise to perform.

In each case, Yoshi is warped to coordinate (0, 0): the top-left corner of Make Eggs, Throw Eggs; he must then flutter around nine times while holding right on in order to reach solid ground. Clearing the stage causes the game to think that Yoshi had cleared the stage he had originally warped from, and the score he obtained upon completion carries over to the starting stage as well.

Zombie Yoshi
This glitch must be done in King Bowser's Castle, in Door 1. The player must go to an area where a ! Switch near a long lava pit can be found. The player would normally have to hit the switch in order to get across the lava, activating the Dotted-Line Blocks. If the player jumps in the lava, in the direction of the switch, Yoshi performs a last jump, since he burned himself. If done right, Yoshi hits the switch, and comes back to life. The music stops, and the player controls Yoshi normally, even though he was supposed to lose a life. If the player attempts this glitch while Yoshi only has one life left, he has zero lives, as shown in the pause screen. However, if the player repeats this process, Yoshi instantly gets 999 lives.

This glitch can still be performed in Yoshi's Island: Super Mario Advance 3.

Airsickness
Attempting to use a melon's effects while riding a Lakitu's Cloud, at least on 5-1: BLIZZARD!!! where both watermelons and Lakitus occur naturally but may happen elsewhere with the use of items, causes Yoshi to use up all of the watermelon's effects uncontrolled. Yoshi spits out all watermelon seeds, and if he destroys the cloud while riding it with the red or blue watermelon, he uncontrollably spams his watermelon and then tongue afterwards, freezing the player in place until death or reset.

Blue Yoshi on World 6 map
When the player arrives on the World 6 and get to at least 6-6, they can see Blue Yoshi, despite Green Yoshi being playable in the last level. The color is fixed upon reaching 6-8 or pressing right on the D-Pad to reset the Yoshi's positions.

Minor glitches
NOTE: Some minor glitches are normal and may be easy to execute.

Wall clipping
In World 1-1, if the Piranha Plant after passing by the third Flower eats Yoshi facing the wall, he will spit Yoshi out being clipped into the wall. The wall will push Yoshi backwards correcting the glitch.

A similar result can be achieved in World 1-5: when Purple Yoshi rides the green platform as far as it goes, he should stand on top of the platform and duck down. If the player waits for the autoscrolling screen to push Purple Yoshi, he should be able to clip into the wall.

Blocky map
In some stages with Fuzzies (for example, World 1-7), as soon as the Fuzzy touches the player and the screen changes, the player should quickly press and  at the same time to return to the map section. This will make everything on the map blocky. The player can fix this by entering another level and completing it.

In Yoshi's Island: Super Mario Advance 3, the pause menu is slightly different, in which the player cannot quickly press and  at the same time.

Red Koopa Troopa stuck inside a wall
In World 4-5, at the final big hill, a Red Koopa Troopa will appear. Yoshi should jump on it to cause it to come out of its shell, then wait for it to hop back in. When the shell is shaking, Yoshi should jump on the shell again. The player should repeat this one more time, and if the shell is taken away or destroyed, the Red Koopa Troopa will get stuck inside the wall.

Blocks spawning at the same time
In World 2-1, after going through the falling blocks, Yoshi should enter the secret ! Switch room. After exiting the room, he should head back to where the blocks fell and they will all spawn and fall at the same time, clipping through each other and creating a huge quake.

In Yoshi's Island: Super Mario Advance 3, a flipper has been added after going through the falling blocks, making it impossible to go back to trigger falling blocks.

Hootie the Blue Fish softlock
In some stages where Hooties appear (e.g. World 3-8), if the player aims an egg shot and throws it at the same time when Blue Yoshi enters a Hootie's mouth, Blue Yoshi will get stuck in the air unable to move. If the Hootie leaves the screen during this time, the game will be softlocked.

Super jump
In World 3-3, after Yoshi steps on a Stretch and it becomes flat, he should aim an egg shot and jump at the right timing to perform a super jump. This happens by holding the and  buttons in quick succession.

In World 4-8, a similar glitch occurs during the Hookbill the Koopa boss fight. If the player ground pounds on the final hit before Hookbill lands on his back, Yoshi will go up into the air and off-screen. This also makes Hookbill slide across the stage and stopping to the edge of the wall, and also affects the key cutscene that plays out afterwards; however, if Hookbill is facing right instead of left of the edge of the wall, the game will freeze, forcing the player to reset the game.

Super Star Softlock
In World 4-1, there is a Super Star on a platform that is blocked by a destructible wall. Yoshi can actually bring a Shy Guy to this area and use the extra height from bouncing off of its head to get on the platform behind the destructible wall and collect the Super Star. If Yoshi did not have any eggs before doing this, the player will be trapped because Superstar Mario cannot destroy the wall, nor can Yoshi without the use of eggs. The only way to get out is by either resetting the game, using a power-up item from bonus games, or exiting the level if it has been completed.

Bridge out
This glitch only works in the Game Boy Advance version, Yoshi's Island: Super Mario Advance 3, due to the recoded pause screen. In the level Touch Fuzzy, Get Dizzy, there are red and yellow bridges at the end that break into pieces if Yoshi pounds the ground. If the player pauses the game while ground pounding the bridge but before hitting the water, Yoshi and the bridge pieces will continue to fall, with the pieces soon warping to the top of the screen. If the player unpauses after Yoshi drops under the water, a life will be lost.