Viggo Mortensen says that, during the costume fitting for the Nazi uniform, he felt that it was never quite fit right. He eventually realized this was due to his reluctance to see himself in Nazi colors.
Adolf Hitler fought in the First World War in the 16th Reserve Regiment of the Bavarian Army. The regiment was later renamed the List Regiment in honour of its late CO. He was promoted to Gefreiter (Lance Corporal) and was a regimental message-runner. These facts support Maurice's amusing fantasy of having given Hitler an order during the war (and being saluted in return).
Ernst Eduard vom Rath was a German diplomat stationed in Paris who was shot and killed by the young Polish Jew Herschel Grynszpan. The death of vom Rath served as the casus belli for Hitler's Kristallnacht orders. Although the Nazis eventually got custody of Grynszpan when France fell, they never staged a trial and the motives for vom Rath's murder remain unclear. Historians have speculated that vom Rath and the younger Grynszpan (17 at the time of the murder) were involved romantically, and this somehow precipitated the murder.
The music played at the end by the Jewish prisoners is Gustav Mahler's first symphony, third movement. This movement uses as one of its themes a parody of the popular children song "Frère Jacques", and the whole symphony borrows heavily from one of Mahler's song cycles, Lieder eines Fahrenden Gesellen. The last song, "Die zwei blauen Augen" (The two blue eyes) can be heard sometimes during the movie, as in the end of the movie shoot and as part of the symphony's movement being played.