Back To The Future 2 - Locked Garage?
This happens at the part when Marty goes back to 1955 to get the almanac.When old Biff and young Biff leave the garage with Marty in the back seat they lock the garage. This is emphasized because Marty becomes trapped. When Biff then returns to the garage to leave for the dance he just opens the garage. There is no time between shots for him to have unlocked the garage and there are no chains hanging from the door.
copy of back to the future part II