Factual error: In the final scene there is a shot which shows a Land Rover in the distance. Land Rovers were not built until after World War 2.
Factual error: When Hauptmann Lutz ditches the radio in the quicksand, it promptly sinks. This is at least debatable, since a radio of that era would've contained a substantial amount of buoyant wood. However, when Sgt. Pugh later throws his incriminating shirt into the quicksand, it is pulled down by a mysterious force. It certainly isn't Archimedes' Principle and looks more like a hidden string to the bottom of the tank on the sound stage.
Factual error: In the closing shots when Van der Poel is being driven away by the Military Police there is a Land Rover parked in front of a building. Land Rovers were not put into production until 1948 so it is seven years too early. (02:03:26)
Factual error: Several British soldiers are seen carrying Lee Enfield Mk. 4 rifles which were not introduced to general service use at this time.