From Sonic Retro
Various unused sprites found through debug or other methods.
The continue jingle from Sonic the Hedgehog. Unused because there are no continues in this game.
Scrap Brain Zone
Using Game Genie code IEVAZZAA will take the player to the remnants of Scrap Brain Zone after losing a life. The title card reads "Final Zone Act 1" and uses tiles from Star Light Zone and Final Zone, using the former's music.