Deliberate mistake: When Raza is chasing the "empty" train, as it goes over the trestle just before he stops it, you can see the engineer in the train's engine.
Deliberate mistake: When the fight first begins on deck of the sub, a henchman jumps from the hatch and picks up a wrench that was lying on deck. If the sub just surfaced, where did that wrench come from?
Deliberate mistake: Montag's hair gets intermittently shorter, longer and shorter again (and acquires a "cow lick" that wasn't there before) near the end of the film. (Oskar Werner had clashed with Francois Truffaut and deliberately had his hair cut to spite director.)