Faster reload
Immediately after pressing L to reload, press L3 to block. When L3 is released, your weapon will be instantly reloaded.

Completion bonuses
Successfully complete the game to unlock the "Trailer" option and all entries in the "Gallery" and "Sound Test" screens.

Expert mode
Successfully complete the game on the normal or hard difficulty setting to unlock the expert difficulty setting.

Spread fingered gesture
Hold Block, then press White, Black.