Finish the game under the normal or hard difficulty to unlock the expert difficulty setting.
Right after pushing L to reload, press L3 to block. When L3 is released, your weapon will be instantly reloaded.
Spread fingered gesture
Hold Block then press White, Black
Alternate ending sequence
After Alex becomes affected by the Pendulum effect and begins to float outside the helicopter, have Derrick walk out of the helicopter towards her. You will also enter the Pendulum effect and can enter the future with Alex to start an alternate ending sequence.
After finishing the game you will unlock the "Trailer" option and all entries in the "Gallery" and "Sound Test" screens.