Factual error: In the scenes of Ian Fleming in the Naval Intelligence HQ, there is a map of Scandinavia on the wall. The map already has the post-war borders of Finland on it.
Character mistake: When the American hands over the wills to Ian Fleming he calls him Lieutenant Commander, but when Fleming turns up at the camp he has gold braid on his cap - only commanders and above wear gold braid. Also they kept calling the RAF guy Flight Sargent but he didn't have a crown above his stripes.
Factual error: During the assault on the radar station, the commandos seize a German machine gun and employ it effectively. The movie takes place in 1940, yet the machine gun is an MG42, which was not issued until 1942.
Suggested correction: It was an MG34, not an MG42.
Factual error: The SS commander wears the collar patch of a Hauptsturmführer (captain), but the epaulettes of an Unterscharführer (corporal).
Factual error: Flight Sergeant Rollright wears the three chevrons of a sergeant, rather than the three chevrons and a crown of a flight sergeant.
Factual error: Ian Fleming wears First World War service ribbons. Fleming was ten at the end of the First World War.