Cheat mode:
Hold A + C + Start on controller two at the Sega logo and continue to hold these buttons during the duration of the code. Hold A + B + C, and press Start(2) on controller one at the title screen. Release all buttons. A cheat menu with difficulty, lives, and continue options will appear.

Extra continues:
Press A + C + Start on controller two at the Sega logo. The phrase "Insert Coin" will flash at the title screen to confirm correct code entry.