Extra lives and continues:
Hold Down + A + B before the title screen is displayed. With those buttons held, press Start at the title screen. The screen will flash red to confirm correct code entry. The game will begin with five lives and five continues.

Super jump:
Press Up(2), Down, Left, Right, B, Start at the title screen.

Hint: Easy kills in level 2:
When in level 2, the tree level, you can hang from the ceiling and press A + Down to throw the disc down and easily kill enemies. You can also do this from the side. Go to the side of the tree and press Left or Right (depending on which side of the tree you are on) and press A.

Hint: Extra life in level 2:
Punch the same bug five times in level 2, the tree level, to get an extra life.