Factual error: The villain holds Magnum at gunpoint with a weapon with a silencer. Which is useless, the gun being a revolver. (00:41:20)
Factual error: Richard Johnson appears in the end credits as "Brigadier General Alistair Ffolkes, Royal Army", and is consistently referred to that way by Higgins and Hooker. The rank was abolished in 1921, the Royal Army would have him as as a Brigadier or a higher rank.