Continuity mistake: In the scene where Willem Dafoe is conversing with another male British agent as the German paratroopers invade, a British female worker passes him as he is about to go down the flight of stairs. As he reaches the ground floor, she passes by him again as she goes up the same stairs he just came down - seemingly far too quick to be possible.
Trivia: When Almasy returns to the cave, he is wearing a German Wehrmacht issue tunic. From a distance, his outfit looks like German Army. However, looking closer, it is completely without insignia (other than plain privates's shoulder insignia). Makes perfect sense that the German Army would most likely not give him a piece of regulation uniform. If this is intentional, it shows perfect sense for detail.