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.
Great sites
Mistakes
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. See more...
Atonement mistakes
Continuity: In the love making scene in the library, Robbie pulls down the strap of Cecilia's dress and she pulls her arm out. In the next shot it is up and over her shoulder again.
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.