The Special Stage Secret
If you have the game Sonic & Knuckles, you can access a special bonus stage. To activate, insert your Sonic Spinball cartridge into the lock-on Sonic & Knuckles, then turn on your Genesis. Wait for a screen with Sonic, Tails, Knuckles and Robotnic and the words, "No Way". Now hold A + B + C and you're ready to play.
Debug Mode (Game Gear Only)
From the Options screen of the Game Gear version, play SFX O,9,0,1,6,8. In the game, pause, then press 1 and 2 simultaneously. Use the D-Pad to move, and press start to go back to normal mode.
Level Skip (Game Gear Only)
From the Options screen of the Game Gear version, play SFX 0,2,1,5,6,6. In the game, pause, then press 1 and 2
simultaneously. Press down to skip to the boss, then the bonus stage, then the next level, etc.
Zoom Mode (Game Gear Only)
From the Options screen of the Game Gear version, play SFX 0,2,1,1,6,6. The screen will show a zoomed in version of the game when you play.
Fast Background Music (Game Gear Only)
From the Options screen of the Game Gear version, play SFX 0,4,2,5,5,7.