Continue
On Level 2-3, when the screen shows "Game Over," quickly press Up, Right, Down, Left, A, B. You will then be given the option to Continue/Start. Press Start to continue the game!
On Level 4-6, when the screen shows "Game Over," press Up, Down, Left, Right, B, A, A. You will then be given the option to Continue/Start. Press Start to continue the game!
On Level 7-9, when the screen shows "Game Over," use Controller 2 and press A, A, B, B, Down, Up, Right, Left. You will then be given the option to Continue/Start. Press Start on Controller 1 to continue the game!

Extra Lives
Select the two-player game where you can knock out the other player (2 Player B). Clear the first screen of enemies. Start knocking out the other character. Every time you defeat him, you receive 1 extra life.

Level Select
Enter these codes at the title screen:
For missions 1-3: Up, Right, Down, Left, A, B (do not press start)
For missions 4-6: Up, Down, Left, Right, B, A, A (do not press start)
For missions 7-9: A, A, B, B, Down, Up, Right, Left (on controller 2)