Call Of Duty 4: Modern Warfare

Fall through floor in Intervention mission Go to the room with the nuke you are supposed to find. Go down the ramp, then go under it. Crouch, then with your back to the bottom of the ramp, stand up. After a few tries, you should fall through the floor. You can kill enemies from down there, but you cannot get further in the mission. You must kill yourself or reset the game to get back up.