Bunker

Adding to what another user wrote a few weeks back, RE WW1 (The Great War) versus WWII. Not that I've watched through all this (yet) but within a short amount of time watching it was obvious that they attire was WW1 just due to the Brodie helmet Mark 1. But also the barbed wire and just the title itself of "Bunker" was a bit of a giveaway.

There were significant differences between the two wars, in particular trench warfare in the Great War as it was the first large-scale war after the Industrial revolution and where battles hadn't quite become accustomed to these technological changes yet. A film based on WWII would not have used this backdrop, more likely something like the Pacific theatre perhaps + of course the attire would have been different looking ie. A Mk III Helmet for the British for example.

And of course that The US were never allies with the Germans, in either war.