Level select
You need to press Down, L2, Up, L1, Square, Down(4), Up.

Extra life
You need to press Up, Down, Square, L2, L1, Down, Up, Down(2x's), Up.

Gallery unlocked
You need to press Square, Down, L2, Down, L1, Square, Up, Square, Down(2x's).

Extra 10 magic pickups
You need to press L1, Down, L1, L2, Square, Down, Up, Down, Up(2x's).

Extra 4 door keys
You need to press Square, L2, Down, L1(2x's), Up, Square, Down, Up, Down.