In the Japanese version there are coins at the end of the last level in the Special World that spell out the words "YOU ARE SUPER PLAYER!!". This error was fixed in the Western localization, with the coins now spelling "YOU ARE A SUPER PLAYER!!"

In the western localiztion of the game, the Special World's levels are all named after 90's American surfer lingo, with the names being Gnarly, Tubular, Way Cool, Awesome, Groovy, Mondo, Outrageous, and Funky.

However in Japan the first two levels are named "Fun Course", third and fourth are named "Even the Mario Staff is Shocked Course", fifth and sixth are named "Specialists' Course", and seventh and eight are named "Championship Course". None of the shared names are even differentiated through numbers, like “Fun Course 1” or “Fun Course 2”.

Among the files included in the Gigaleak, a massive 2020 content leak of internal data from Nintendo, is a tileset associated with Super Mario World depicting a Bullet Bill variant so big that it nearly occupies the entire screen. While the idea was scrapped in favor of the much smaller, but still large Banzai Bill, it would eventually be revisited in New Super Mario Bros. Wii with the King Bill enemy.

If you stare at a Boo for around 13 seconds, the Boo will make a funny face back. If you stare at a Big Boo for around 25 seconds, the Big Boo will briefly peek out from hiding in its hands to see if you are still looking.

An anime re-telling of the game was produced titled Mario to Yoshi no Bouken Land (translated to Mario & Yoshi’s Adventure Land), and released exclusively in Japan in 1992 for the Bandai VHS system Terebikko. Using the fake phone device, players would interact with it when prompted to answer questions and press one of four colored buttons. The VHS animation ran for twenty-eight minutes.

In the Super Mario World & Yoshi's Island Developer Interview with Nintendo, Takashi Tezuka stated that Mario was originally going to ride a horse instead of Yoshi. However, it felt out of place for a "reptile" world, and was changed to look both like a crocodile and a turtle. A similar concept was almost given to Mario in Super Mario 64, but was later given to Link in Ocarina of Time as Epona.

In the SNES game, the Boos and Big Boo are light blue. In the Game Boy Advance game, the Boos and Big Boo are white.

Bowser and the Koopalings all have 3 fingers on their hands in the SNES game. In the Game Boy Advance game, Bowser and the Koopalings all have 4 fingers. His arms were also recolored.

In the SNES game, all of the Yoshi eggs have dull brown spots on them (besides Green Yoshis). In the Game Boy Advance game, the Yoshi eggs all match the color of the Yoshis inside them.

In the Game Boy Advance game, Princess Peach has blue earrings, lighter hair and a lighter pink dress. These changes more accurately represent Peach's current look. In the SNES game, Peach has pink earrings along with a darker pink dress and hair.

A power-up can be found lying on the ground in the last room of #3 Lemmy's Castle. In the SNES game, the power-up is super mushroom; in the Game Boy Advance game, the power-up is a feather.

In the SNES game, when fighting Bowser, only the box with the reserve item appears at the top of the screen. In the Game Boy Advance game, the full HUD is displayed.

In both versions of the game, the seventh room of Bowser's Castle contains statues that spit out flames. The first statue in that room, which appears in the SNES game, is missing in the Game Boy Advance version.

The player can re-play a castle by simultaneously pressing the L and R buttons in the SNES game. In the Game Boy Advance game, the player cannot re-play a castle until Bowser is defeated; after Bowser is defeated, the player can then re-play the castles by entering it the same way they enter any other level.

In the SNES game, punching a Climbing Koopa awarded 100 points. In the Game Boy Advance game, this was changed to 400 points.

Points awarded in the SNES game are lower than the Game Boy Advance game for defeating Charging Chuck. Also, in the Game Boy Advance game, coins are awarded for defeating Charging Chuck with fireballs.

Yoshi turns into Blue Yoshi if he has wings when a level is completed in the SNES game. In the Game Boy Advance game, Yoshi will not change into Blue Yoshi if he has wings when completing a level.

Yoshi can spit the key out after entering a keyhole in the SNES game. This was removed from the Game Boy Advance game.

In the SNES game, Mario and Luigi can not spin jump on some enemies that they can in the Game Boy Advance game, such as Boos and Podoboos. Also, in the Game Boy Advance game, Yoshi can jump off of fish enemies.

By holding the run button, Mario and Luigi can climb vines faster in the Game Boy Advance game.

In the SNES game, Yoshi will always produce an egg containing a mushroom when he eats ten red berries. In the Game Boy Advance version Green Yoshi will produce an egg with a mushroom, Blue Yoshi will produce an egg with a feather, Red Yoshi will produce an egg with a Fire Flower, and Yellow Yoshi will produce and egg with a Starman.

In the SNES game, Yoshi has orange arms regardless of his body color, though he has green arms on the SNES box art. In the Game Boy Advance version, Yoshi's arms are the same color as his body.

In the SNES game, player 1 controls Mario and player 2 controls Luigi. In the Game Boy Advance game, the player can choose to play as either Mario or Luigi by pressing the R button on the world map. Additionally, in the SNES version Luigi is an exact copy of Mario with a different color palette. In the Game Boy Advance version, Luigi was changed in several ways including:
• Luigi is taller and skinnier than Mario and more closely resembles his modern apperance. Luigi also wears blue overalls instead of his purple overalls from the SNES version.
• Luigi jumps higher, moves slower, and scuttles in mid-air much like he does in Super Mario Bros. 2 (U.S. version). He also runs slower and has worse traction than Mario.
• Luigi flies higher with his cape than Mario, but also flies slower.
• Fireballs from Fire Luigi bounce higher.
• When Luigi rides Yoshi, Yoshi doesn't instantly eat enemies; Yoshi can spit enemies out, and use some of them as weapons, but swallows them after 7-8 seconds.
• All coins will fall out of a block if Luigi hits it, whereas the coins come out one-by-one when Mario hits the same block.

In the Game Boy Advance game, earning at least 10 lives consecutively will cause a flower and the number of lives earned to scroll across the screen.

In the SNES game, the player can only save after completing certain stages or finishing any Ghost House or Fortress. In the Game Boy Advance game, the player can save inside of a course or on the world map; the Game Boy Advance game also saves the player's power-ups and life count, whereas the SNES version starts the player out as Small Mario with 5 lives each time a saved file is loaded.

In the Game Boy Advance game, different colored Yoshis can be found in question blocks on regular stages after finding each colored Yoshi on Star Road. Cape Mario/Cape Luigi can find a blue Yoshi, Fire Mario/Fire Luigi can find a red Yoshi, and Super Mario/Super Luigi and Small Mario/Small Luigi can find a yellow or green Yoshi. In the SNES game, only green Yoshis can be found in question blocks outside of Star Road and the Special World.

Ghost houses and Fortresses do not have Dragon Coins on the SNES version, but appear in every level in the Game Boy Advance version. Because of this change, some level designs were reconfigured. The Dragon Coins will also turn into Peach Coins (after a cutscene) if all five Dragon Coins are collected in every single level in the Game Boy Advance game.

In the SNES version, the maximum number of lives a player can have is 99. In the Game Boy Advance version, this was changed to 999.

In the SNES version, enemy changes and Autumn-colored levels appear after completing the Special World. In the Game Boy Advance version, all 96 exits must be cleared instead.

Additionally, the Game Boy Advance version includes a cutscene showing Luigi in a balloon tossing out masks to the Koopas after unlocking the Autumn-colored levels, whereas the changes in the SNES version are first seen when entering Yoshi's house upon exiting the Special World.

Galoombas and Pokeys also have different appearances in the Game Boy Advance version, along with Koopas, Bullet Bills and Piranha plants like the SNES version.

In the SNES game, when Mario or Luigi gets hurt while having a power-up (i.e. fire flower or cape), Mario and Luigi will become Small Mario/Small Luigi, as they did in Super Mario Bros. In the Game Boy Advance game, Power-up Mario/Power-up Luigi will become Super Mario/Super Luigi when they are hurt, as they do in Super Mario Bros. 3. In both versions, if Super Mario/Super Luigi get hurt, the reserve item in the box at the top of the screen will drop down.

In the SNES version, the "Top Secret Area" stage is a yellow dot on the map. In the Game Boy Advance version, a smiling bush represents the stage.

In the SNES game, the timer for Bowser's Castle is 400 seconds; there is no time limit when fighting Bowser. In the Game Boy Advance game, the timer was increased to 800 seconds if entering through the front door and 600 seconds if entering from the back door due to the timer continues when fighting Bowser.

In the SNES game, the "Top Secret Area" stage does not have a timer. In the Game Boy Advance game, the "Top Secret Area" has 200 seconds on the timer.

A status menu is accessible on the world map by pressing the Select button on the Game Boy Advance version. The status menu allows the player to see total play time, score, the number of exits found by each brother, whether Princess Peach has been saved, and whether all of Dragon coins have been collected.

After completing all exits on every level, a stage select screen will also become available that will take the player to any chosen level.

In the SNES game, the maximum number of lives a player could have is 99. In the Game Boy Advance game, this was changed to 999.

The international version has several changes to levels when compared to the Japanese release. These include minor graphical changes to fix mistakes or to provide more obvious information to the player, along with several changes to make the game slightly easier.
These changes are also present in the Game Boy Advance release.

The game contains an unused sprite of the word "and", it's not known exactly where this would have appeared, but it was most likely intended to be used as part of the copyright text.

In the SNES release, Yoshi's house has seven berries on it. In the Game Boy Advance release, there are ten berries.

The sleeping fish enemy, known as "Rip Van Fish", will typically chase down Mario upon being woken up. However, if Mario is under the effect of a star power-up, Rip Van Fish will make an effort to flee in the opposite direction of Mario instead.

The grassy pond located half way up "Kappa Mountain", found near the start of the game on Yoshi's Island, is named after the mythological "Kappa" from Japanese folklore, which is often depicted with a small pool of water on its head. The name "Kappa Mountain" only appears in the game's instruction manual.

If you play the last level of the special world in the Japanese version of the game, at the very end of the level a lot of coins will spell out "you are super player". To fix any grammatical issues, the international version changed this to spell out "you are a super player".

In the Japanese version, Reznor's name is Bui Bui which is labeled on the wooden planks when you battle them in the fortresses. Bui Bui's name was changed to Reznor when the game was localized.

The Reznors fought at the end of Fortresses were named after Trent Reznor from the industrial rock band Nine Inch Nails, similar to how the Koopalings were all named after Famous Musicians.

In an early prototype of the game, the clouds in the sky are reminiscent of old Japanese art. The world it overlooks is a mushroom shape, which resembles the prototype overworld. It would later appear in the Super Mario Advance version of the game.

An unused 5-up logo can be found in the game's data. When used in game, the logo doesn't show up correctly. You can get a 5-up by bouncing on Wigglers, or by using a Game Genie code. It's fully coded, but the actual way the graphics are displayed is incorrect, as their properties are pulled from the code after the table with the score palettes. The 8x8 tiles used are incorrectly flipped horizontally and vertically.

The game's ending shows Mario and Luigi with red and green shoes, despite the cover depicting Mario with brown shoes. Also, both Mario and Luigi wear brown shoes during game play.

Early screenshots of the game show that Raccoon Mario was to return, before being replaced by Cape Mario. A raccoon leaf and a few Raccoon Mario sprites are also present among other early Super Mario World graphics found within the data of a SNES test cartridge, used by Nintendo to test and diagnose the consoles and controllers.

The stage which is shown at the title screen is an unfinished version of the Special World level "Groovy".

The Japanese box art of Super Mario World uses the subtitle, "Super Mario Bros. 4". Even though the subtitle isn't used on the Japanese title screen (or anywhere else) there is a graphic for the subtitle in the game's ROM.

The game originally had a flying cage carried by four winged creatures. Mario would start already in the cage and with an autoscroll script, the cage would move along the level. Although the cage can be found in the code, the graphics for it are incomplete. The cage is likely left over from the 'SNES Test Program'.

Spike Tops originally had six legs when they debuted in Super Mario World.

The two ammunition-based enemies in Super Mario World are Bullet Bills and Torpedo Teds. This would make their referred-to names 'Bill and Ted', a possible reference to the film "Bill & Ted's Excellent Adventure". Their Japanese names translate as "Killer" and "Torpedo" respectively, meaning this reference would have been made by the Nintendo of America localization team.

The symbol that you find at the top of "Special World" is really the Super Famicom logo in Japan, and the SNES logo in Europe.

A hidden level is found in the game's code, which seems to be a test level. All unused level sections are filled with this test level, so over 200 copies of this level are in the game.

If you wait in the special world for a few seconds the music will change to a remix of the original Super Mario Bros theme.

The manual reveals that the sunken ghost ship is actually an air ship that was used by the Koopalings in Super Mario Bros. 3.

The seemingly random symbol on the mail box of Yoshi's House is actually the logo for Japan's postal service.

In the Japanese version, Yoshi can eat the dolphins. This was removed from the international release. It's thought it was removed because of the different cultural views towards dolphins, or simply to make the level easier to finish, as the dolphins can be used as platforms. This was added back into all versions of the Game Boy Advance version.

In the Japanese games, Super Mario World's "Forest of Illusion" and The Legend of Zelda's "Lost Woods" share the name, "Mayoi no Mori" (Lost Forest). All the standard exits in the Forest of Illusion send you around in circles which is comparable to the Lost Woods circling you back to the entrance after a wrong turn.