All missions
Press [X], [L2], [Triangle], [R2], [Select] at the title screen to unlock all missions.
Invincibility
Begin a mission, then pause game play. Press [L1], [R2], [L2], [R1], [Select] to become invincible.
All special features
Press [L1], [L2], [R1], [R2], [X], [Select] at the title screen to unlock all specials features.