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. Can't be an Avro Manchester either, they only had two engines and first flew in 1939.
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.
Factual error: After they arrive in Sarajevo they are driving through city and are observing demolished city. There is a red car parked behind three woman. That car is Chevrolet Spark (second generation) that was produced between 2005-2009. Film takes place in year 2000. (00:10:25)