One of the motivations behind making this movie was the indignation of many British World War 2 veterans (and civilians) over the movie U-571 (2000), in which the capture of the Enigma was shown to be done by American navy officers (despite the fact that the makers of that movie had indicated their movie to be a work of fiction and no accurate portrayal of the events leading to the capture of the Enigma).
In the final scene, in London after the war (1946), Hester steps off the pavement and we see double yellow lines painted at the kerbside (denoting No Parking). These road markings were introduced much later.
When Hester takes the enigma machine out of the car and into her flat she does not take the box with the battery. The battery is not seen in subsequent shots. The battery was needed to use the machine.