Successfully complete a level without using a continue to unlock three bonus levels for that difficulty setting. Note: The Master difficulty setting does not have any bonus levels.
Collect 2500 points in the main game, then choose a Mini Game. It will be unlocked. Collect a further 2500 to unlock another, and so on.
Successfully complete the game under the all three initial difficulty settings.
Instead of going forwards towards the goal, turn around and go up the little point. Fall off and land on a platform beneath. There should be another goal there that warps you to level 5.
You can combine the power ups to create combos:
Big Glove + Big Glove = Double Glove
Big Glove + Long = Big, Long Glove
Big Glove + Vortex = Big, Vortex Glove
Big Glove + Big Glove + Long = Super Big, Long Glove
Big Glove + Big Glove + Vortex = Super Big, Vortex Glove