|Super Sonic slot machine panel||Sprite for Pinball bonus stage. Never used in game.|
|F-ball||An unused gumball found in the rolling jump bonus stage. Can be placed with debug mode, though it does nothing.|
|S-ball||A flashing gumball which also does nothing. This was likely give the player their Super transformation if they collected the Emeralds.|
|Platform||An unused platform found in the rolling jump bonus stage which can be stood on. Can be placed with debug mode.|
|Palm Tree||Unseen palm tree graphics. Although these tiles are used in both Sonic 3 and Sonic 3 & Knuckles in the introduction to Angel Island, they are hidden behind leaf sprites. This is how it looks with the sprites layer disabled:|
|Death Egg Holograph Projector||Some machine that displays a holograph of the Death Egg. It can be found by hex editing a savestate of Death Egg, act 2. At address A500 replace 01 with E5 and the most northwestern piece will change to this. Thanks to Gold for finding this.|
Tails is playable in the game through hacking. Unfortunately, most of his sprites are missing. A savestate (info) (50 kB) of Tails in Sonic & Knuckles is available. If the PAR code FFFF09:02 is used in Sonic & Knuckles, Tails will be usable, but just about every sprite of his, except the transformation sprite, will be missing, basically rendering him invisible (unlike when a savestate is used; a different, glitchy sprite is used in place of Tails's original one). However, his sprites used at the end of Sky Sanctuary Zone to run around the collapsing pillar are actually stored in the Sonic & Knuckles' ROM and therefore are visible. The same sprites are used also in the same context in Lava Reef Zone.
If Sound Test is enabled, and any of the Special Stage options is selected, Sonic or Knuckles is taken to the 1st Special Stage. The end of it however, spawns a Super Emerald. This is when the special stage is marked as clear, but the normal Chaos Emerald amount doesn't rise. The Super Emerald amount will rise, but it has pretty much no effect due to Super Emeralds being unobtainable. This bug WILL allow for the 8th Emerald to be collected once the other six have, though.