Disable Background Music
During a space-flight level, press A and B simultaneously, and do so twice. This will disable the background music. If you wish to do this in a planet-flight level, press Start, then A + B.
Level Skip
During any level, on controller 2, hold Down+Select and press B, B, B. Release both buttons, then press A+Right+Start on controller 2.
Power Up
If you are in the 'Star Stage,' when doing the Level Skip code, you will repair any damage, and if you are in the 'Base Stage,' you will gain 9 ships in reserve.
Shield
When you get a Shield in a planet-flight level, press A and B on Controller 1. Then press Up or Down and you can rotate the ship instead of sliding up or down.