Revealing mistake: Watch the back projection of the Great Northern desert in the train carriage windows. At one point a lorry appears, waiting at a level crossing for the train (that the film was shot from) to pass.
North West Frontier (1959)
1 revealing mistake - chronological order
Directed by: J. Lee Thompson
Starring: Herbert Lom, Lauren Bacall, Kenneth More, Wilfrid Hyde-White
Factual error: The Maxim guns are mounted on Mk IV tripods, not introduced until 1906 (plus with direction dials fitted, which didn't get introduced until 1915), and metal ammunition boxes are used with them (again introduced in 1915 - they should be wooden at this date).