The RAF is shown using Boeing B-17 Flying Fortresses to bomb the area of the prison. Although the RAF did use B-17s in small numbers during the war, by 1943 all were assigned to Coastal Command for anti-submarine duty over the Atlantic.
About 1:20 into the film, there is a scene where the French police are coming into the town at night. One, on a motorcycle, rounding a corner, seemingly slips on the wet cobblestones and crashes in front of the camera - the shadow of his head flashes across the bottom of the screen and the sound of his presumed crash can be heard.