Atonement (2007) - 4 major mistakes

Deliberate "mistake": In the approach to Dunkirk, Robbie is carrying a pistol, complete with webbing holster. He has no rifle and is carrying a bayonet on his haversack, presumably not having the usual belt frog to carry it more easily. As a Private (this is emphasized in the dialogue) in an infantry regiment, he'd have carried a rifle and not a pistol. Although he might have acquired the pistol during the retreat, he's less likely to have changed his webbing order to match. This may be a deliberate directorial choice. The dialogue emphasizes his natural "officer qualities", and that his prison record has prevented him from becoming one. The wearing of officer's equipment, even if historically inappropriate, also reinforces this and distinguishes him from his comrades.

Continuity: When Briony walks in on Robbie and Celia in the library, the door is slightly ajar (since it's the lamp in the room that catches her attention). But when the scene is replayed from Robbie and Celia's perspective, Robbie shuts the door completely.

Continuity: When Briony sees Cecilia coming out of the fountain (from Briony's perspective), Cecilia steps out of the water with her right foot first. When we see the same scene afterwards, from Cecilia an Robbie's perspective, Cecilia steps with her left foot first.

Factual error: On arriving on the beach at Dunkirk, Robbie is told of the sinking of the Lancastria and the loss of 3000 men. This event actually occurred 17 days later on June 17 1940.