The Twilight Zone: Judgment Night (TV)

During World War II, a confused Carl Lancer finds himself as one of only a few passengers on a freighter, the S.S. Queen of Glasgow, traveling from London to New York. As he sits with other passengers, he begins to realize that he is the captain of a U-Boat that is at that very moment tracking the freighter with a view to sinking it. He also knows that in just over an hour the freighter will be attacked.