When Erickson goes to the "red light" district in Hamburg to make his contact with the underground, the street is ablaze with light from the windows and street lamps, something that would never have been seen in wartime, when blackout precautions were rigidly imposed - particularly in a city like Hamburg, which was a routine and consistent target of Allied bombers.
The story takes place in 1942, but all the women's hair styles and fashions are strictly 1962.
In the Copenhagen street scenes of Danish bicyclists blocking the Gestapo truck pursuing Erickson and the underground leaders, a blue-and-white late '50s car can briefly be seen in the background in one shot.