There appears to be a large amount of Unused Content in FNaF World. Half of the content was never used in the game, but still can be found within the game's files or the game's pre-release. All unused content is below here.
"Adventure" Animatronics Term
As FNaF World was announced, Scott Cawthon called the characters "Adventure animatronics". The term wasn't used in game, however, the copyrights have the phrase, "(Adventure Version)".
Shadow Freddy with Pizza Wheel 2
In one of the teaser screenshots on IndieDB, Shadow Freddy can be seen with the "Pizza Wheel 2" attack. This was changed to the "Esc Key" attack in the final version.
In the Foxy Fighters minigame of update 1.20, JJ has an unused voice clip including a swear that would probably play after Nightmare Chica's plane is shot down. It features her saying:
"Now I'm going to kick your a**! Wait, what? I-I can't say that in the game... "
Locked starter characters
In the game files, images of the icons of the starter characters locked can be found. However, this has never been used in the final game.
Robotic Bear EnemiesIn the earlier photos and trailer of the game, there was a robotic bear similar in appearance to Prototype; it may have been a counterpart or an early design of said enemy. This old design looks similar to the Prototype used in FNaF World: Halloween Edition.
Unused Browboy Sprite
In the game's files, what appears to be a Ballboy with the colors and face of Browboy can be found. Browboy may have originally been a normal enemy, like his FNaF World: Halloween Edition counterpart, or it may have been some type of placeholder.
In the first trailer, there appears to be a Mechrab-type enemy, but with its shell painted gold. This enemy was never used in the game. This enemy could be Mechrab's early design.
"Curse: Haunting" Chip
Files for unlocking a red chip called "Curse:Haunting" are stored between the unlock screens for Pizza:Fury and Block:Unscrew. The chip itself, however, doesn't exist even in the files, and Scott most likely forgot to remove this image when he took the chip out. Presumably it would've used Haunting on all enemies from the start of the battle, similarly to the "Auto:" category of chips. The chip may have been replaced with the green chip Quickstart:Party, which stuns enemies for the first few seconds of a battle.
"Slowstart Enemies" Chip
Before FNaF World was released, there was a chip named Slowstart Enemies. Unusually, the colon is missing from this chip's depicted name.
With Quickstart:Party equipped, the party always acts before the enemies do, while Slowstart Enemies would likely have delayed the enemies from attacking first at the start of each battle. Thus, Slowstart Enemies would have effectively been a redundancy if used in tandem with Quickstart:Party, giving cause for either chip's removal. Slowstart Enemies' place on the Chips menu has since been reassigned to the Block:Jumpscare chip.
There appears to be an unused attack in the game: "Toxic Song". It most likely would've poisoned enemies, as with Toxic Bite, and may have been usable by Phantom Mangle and Springtrap, since their fixed counterparts, Funtime Foxy and Spring Bonnie, are the only characters with Cosmic Song. Phantom Freddy is also a possibility due to the fact that he is a singer.
Within the game's files, there's two unused graphics of the poison status. Perhaps, when enemies got poisoned, they would appear, more like the other status ailments.
There appears to be a file of the chest from Five Nights at Freddy's 4, but open. There's no way to trigger it, and the box appears to have nothing inside of it. It was found in the 1st Glitch World files. It may have been intended for opening chests in the original 3D Overworld, but it also may simply be Scott Cawthon tricking players into thinking the mystery of the box is revealed in the game somewhere.
There appears to be no "Ice Cave" area, despite Scottgames.com originally having a preview of the soundtrack. It may have been replaced by Dusting Fields, a similarly cold-themed area.
Files for a swimming turtle exist in the game, grouped among the fish from DeeDee's Fishing Hole. Given this, it is likely that the turtle was intended to be another catchable creature in the minigame with its own payout tier, or probably function as an obstacle to prevent the player from catching a fish. Strangely, it isn't robotic like all the other fish. This might be a reason why it was dropped from the game. Perhaps Scott Cawthon thought it didn't fit in.
Diagonally Walking Freddy Sprite
The trailer for FNaF World showed Freddy walking diagonally in the 3D overworld. Although Freddy can now walk diagonally in the update 1.20, the sprite is still unused.
"Strength" Number in Character Select Menu
In the "Character Select" menu, there appears to be a file of how much strength a character has, and it is seen in the MFA. It is never shown to be used in game however.