Early in the film, Bower is talking to Heinzmann. Bower is holding his cigarette vertically because he has a long ash. The POV switches and Bower has his hand down and cigarette horizontal, still with a long ash on it and he quickly taps the ash off into the ashtray.
During Bower's escape, he is seen untying and getting into a simple row boat, but in the next long shot he is getting into and moves off in a boat with an outboard motor.
In two scenes the characters refer to their country as "East Germany", this would not have been the case as citizens of the republic would use the official term "The GDR" (in English) or ""DDR" in German or simply "The Republic/Republik". Using the term "East" Germany gave recognition to there being a "West" Germany - something heavily discouraged at that time in the history of the GDR.
When one of the actors is referring to Magdeburg whilst holding a map, the map title is "Deutschland" (Germany). Maps in the East would have been titled Deutsche Demokratische Republik (or simply DDR). This may have been a West German map (which would have been titled "Bundesrepublik Deutschland) but highly unlikely as the East wouldn't have been included without a separation of states.
The license plates of the police cars in Leipzig correctly begin with "VP" (for Volkspolizei) , but the next two digits should be "13" (for the Leipzig district), not the "23" used.
At the end of the film when Montgomery Clift shouts, "Don't move him!" his lips are clearly forming other words.
During Bower's escape at night, a lot of thunder is heard, but no lightning is ever seen, even in reflection off any object.
When Frieda goes to the cabinet after asking James if he wants beer or wine, the arm of the boom mic operator is visible in the glass reflection on the left as well as a crew member in a hat on the right.