In the last 10 minutes of the movie, a character is shot by several other characters.
With each of these shots, an empty shell casing should have been ejected from the rifles (M1 carbine and M1). In addition, the empty brass would have made a noticeable "tink" sound as it hit the stone floor in the cellar.
Throughout the picture, German infantrymen use what seems to be some variation of the water-cooled Browning 30-caliber machine gun, which was a U.S. weapon. Also, the German tanks don't resemble any Panzers in use during World War II.