Factual error: Near the beginning of the film before James McAvoy heads up to the house for the evening meal, he is seen looking up through a skylight when a Lancaster bomber slowly flies overhead. At the time it was was supposed to be 1935. The Lancaster bomber did not fly until the beginning of 1941. And if it was supposed to be an Avro Manchester, then they only had two engines.
Factual error: Hadrian's Wall is facing the wrong direction. The Wall was built to defend Britannia from the Picts in Scotland; therefore, its front should face north. However, as the Romans approach it from the south, they are greeted by the sheer face of the Wall.
Continuity mistake: While discussing her bodily changes during adolescence, Marji says her left foot became enormous, but the scene shows her right foot growing larger.
Continuity mistake: When being shot at by the angry waiter, the right hand door mirror was hit by the rifle shot. A few seconds later a view shows only a very minor hole in the glass, and no damage to the rest of the mirror. Surely a rifle shot would have caused more damage to plastic and chrome trim, almost surely passing right through. (00:30:20)airhead