In the chapter where you must find Capt. Keyes in the swamp, there is a secret area you can reach from the beginning. When Foe Hammer says "The last transmission from the captain's drop ship was from this area. That was over twelve hours ago.", immediately keep pressing [Grenade], but do not move. After a few seconds, the drop ship will take back off while you are still in it. It will fly around for approximately 20 seconds and then crash. Exit the drop ship, and walk directly away from the ship until you reach a clearing. Move towards the center and out of the fog to see a marine. He will not move or say anything unless you shoot him in the foot with your pistol.