Deliberate mistake: When we first see Eric Lidell, it is 1920 and he has just returned from China to his homeland of Scotland. Eric would've been 18 years old in 1920. Ian Charleson, who was 31 at the time the film was made, looks his own age.
Deliberate mistake: After the black ninja and white ninja clash swords for the first time, the black ninja pretends to put his sword in its sheath, which is slung over his back, rather than actually doing it.