Debug mode:
Press A(2), B(2), C(4), B(2), A(4), B(2), C(2) at the options screen. David Perry, the game's programmer will also appear.

Level skip and invincibility:
Press Start to pause game play, then press C, A, B, C, B, A, C, A, B, C, B, A, C. A sound will confirm correct code entry. The current level will be completed. Spot will be invincible when the next level begins. Alternatively, Press Start to pause game play, then press A, B, C, B, A, C, A, B, C, B, A, C + Start to end the current level and gain a bonus stage.