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.

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

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.

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.

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.

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.

In the western localization 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".

Blue Beach Koopa Troopas launch themselves off slopes to ostensibly demonstrate momentum physics. However, the physics are actually faked, and instead of using actual momentum, the Koopas are simply programmed to jump whenever they reach an upward slope. This only happens to Blue Koopas who spawn into the level without a shell, and those knocked out of their shells will operate as normal when approaching similar slope configurations. While these Koopas appear shell-less in a handful of courses, only Cookie Mountain and Groovy include ramps they can jump from.

After rescuing Princess Toadstool, a set of four fireworks will shoot up and explode in the sky. If you hold Up on the D-Pad just before the fourth heart-shaped firework appears and keep holding it until the credits roll, Mario's walking animation will be glitched so that he keeps switching between the poses for when he is sprinting and when he looks up.

The sounds used for Yoshi's voice in Super Mario World were created by composer Koji Kondo by playing an orchestral hit keyboard preset and pitching it both higher and lower. This sound would go on to be used as Yoshi's voice in several of his appearances throughout the Mario series, even in some instances after Kazumi Totaka became his voice actor.

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.

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.

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

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

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.

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.

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.

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.

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