Fall

Fall is a special event present in Super Mario World and its remake Super Mario World: Super Mario Advance 2. This event changes the appearance of certain enemies, and alters the colour palette of the overworld map of Dinosaur Island to reflect the season of fall. Fall is triggered by completing Funky in the Special World in Super Mario World, and beating all 96 levels in the remake. Once these prerequisites are reached, a short cutscene is shown, at which point Fall is unlocked. Once activated, these changes cannot be reversed.

Dinosaur Island
Fall causes Dinosaur Island to change colour, with green objects becoming brown and brown places becoming green. Everywhere on the overworld map is affected, including places such as the Valley of Bowser. Although all of Dinosaur Island is changed, the water on the overworld map remains the same colour, and the visual appearance of the levels is not affected. The intro of Super Mario Advance 2: Super Mario World will show Dinosaur Island in Fall at the start and end.

Enemies
Various enemies have their appearance changed in Fall. This change affects everywhere else in the game enemies appear in, in-game or on menus. This change only affects their look, thus they will continue to act the same.

These errors were fixed in the remake.
 * Overworld palettes invert Green to Brown and Brown to Green, but water do not change palette; (beating Special World).
 * Galoombas will be yellow and wear sunglasses (SMA2 only).
 * All Koopa (Para)Troopas become (Para) Mask Koopa Troopas.
 * (Jumping) Piranha Plants become (Jumping) Pumpkin Plants
 * Bullet Bills become Pidgit Bills. In SMW only, there is a quirk that causes the diagonal and vertical Bullet Bills of Vanilla Dome 4 do not change.
 * Pokeys' segments turn into saws (SMA2 only).
 * All Green Mask Koopas and their shells become Yellow, with exception for Para Mask Koopas.
 * All Red Mask Koopas and their shells become Blue, with exception for Para Mask Koopas.
 * Intro and title screen show changed enemies (SMA2 only).
 * All Kamikaze Koopas have their multicoloured shell transformed into a multicoloured Mario mask shells.

The intro for Super Mario World: Super Mario Advance 2 and the titlescreen demo of Groovy will change the enemies to his Fall form (if they have one), and the ending of both games will show enemies in their Fall form during the credits.

Trivia

 * It is incorrectly stated on Gnarly of Super Mario World: Super Mario Advance 2 that completing all the levels in the Special World would give the player a "special present". Although this is true in Super Mario World, it was changed in the remake.