S8·E1 Ring Dem Bells

The Colonel orders the platoon to make a training film with a couple of well-known actors, but unknown to Mainwaring, they're to play the Germans. Although Mainwaring refuses to participate, the rest of the platoon is still ordered to do so. When filming is cancelled, Mainwaring and the men, still dressed as German soldiers, are spotted in the local pub and the alarm is raised.