The German machine gun used in the film is in fact a U.S. 50 caliber Browning.
(at around 7 mins) When the truckload of women arrive at the camp, Ilsa asks, "How many this time?" The doctor replies, "15," but only 13 women get off the truck.
(at around 1h 28 mins) When one of the prisoners uses the machine gun at the end of the movie you hear the shots but as the bandoleer is not moving (meaning that no ammunition is loaded into the gun) it is not firing at all.
Ilsa is referred to as holding the rank of major, but her collar insignia is that of a Lieutenant Colonel or SS Obersturmbannführer.