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 Morph 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 Morph 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 Morph Bubble.

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 Yoshi Egg in other stages
Giant Yoshi 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 Yoshi 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 Yoshi Egg in the air. As soon as the Giant Yoshi 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.

Null / Invisible 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, then spit it out at the Piranha Plant 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, Yoshi needs to eat the Little Mouser and spit it out as soon as Yoshi is near the goal and then jump into the goal roulette. 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, 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 Morph 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.

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 doesn't. First, the player must have Yoshi eat a Grinder and keep it in his mouth until he reaches the checkpoint. 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 can't 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 Yoshi 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.

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 cloud texture, 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.

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.