Any time you see an American soldier in the movie. The American troops are wearing black boots, and the AB guys are wearing black jumpboots. The Army at that time was using a russett brown for all their boots. Even the low quarter boots that were used with the leggings were russett brown. The military didn't go to black boots until the late 1940's early 1950's.
Yes, but little things like that are usually only picked up on by history buffs or living historians. Hell, look at every German in the movie...not a one has a proper German hair cut per Wehrmacht regulations. I'm also sure the producers were trying to save money anywhere they could. Maybe there was a bulk special for black boots :)