The close-ups on the artillery show a modern muzzle-break, not the type used by Russian forces at the time.
When Anton is shot by firing squad he is not tied or restrained.
The insignia on the uniforms of the German officers are printed. In reality they were embroidered.
In the first 40 minutes of the film the Germans are supposed to have been trapped in a position for some time yet:
Defence posts are freshly cut
Barbwire is new and free of rust
All uniforms are pristine clean
The medical officer's white bib is absolutely white with not one blood stain.
Each tank is so clean it looks like it's just been in a car wash, not a battle.
Low budget reenactments, you expect some mistakes - but they should've been more careful with these gaffs. When you first see the small Navy craft and the Landing Craft, they are both flying 50 star flags. A decade and a half too early.