Decent performances but technically poor
Others have mentioned the technical flaws in broad strokes - I'd like to get a bit more specific.
Weapons: Every rifle; submachine gun, and pistol (or revolver) is clearly a non-functioning replica. Probably Denix brand from Spain. The belt-fed MGs and the Brens are also non-functioning, but these appear to be more authentic. No depiction of charging handles moving back and forth, no slide or toggle movement on the pistols, no ejection of spent shell casings, barely any muzzle flash (actually a bit more factual, but a movie audience needs the visual cues). Heck, airsoft guns would have worked better; at least with an electric or gas blow-back weapon you get the simulated functioning to a large degree.
For heaven's sake, even the bolts are forward on the Thompsons and MP40s at almost all times! The real weapons fire from an open bolt: the bolt is normally held to the rear and kept in place by the trigger mechanism. When the trigger is pulled the bolt is released and moves forward to strip a round from the magazine and push it into the firing chamber. As the round seats in the chamber the firing pin strikes the primer with the full forward momentum of the bolt, causing the round to fire. The back-pressure from the firing cartridge causes the bolt to recoil to the rear, where the process begins again, provided that the trigger is still held back for firing.
Uniforms: Someone else pointed out errors with the ribbons and so forth- I'll take them at their word on that. But doesn't a lot of the German SS camouflage look suspiciously like modern German Flectarn pattern? Not every bit- the production team clearly engaged many reenactors as soldiers. But enough to make me notice. Share what you observed if you agree or disagree.
Tactics: Straight from Sgt. Rock comic books! Both Allies and Germans standing in large clumps upright in the open and blasting at each other with endless magazines, ammo belts, en-block clips, and so forth. Not a single MP40 stock was unfolded to it's normal firing position. The military advisor should refund his fee to the production.
The vehicles looked decent- most appeared pretty close to the real deals, especially the jeeps and Kubelwagons. Any more thoughts here?
For a 3 mil USD project they sure dropped the ball on the last hundred meters. All of the weapon effects can be added in post-production using cheap or free templates in AfterEffects, to name one resource. The death scene of the one soldier had him with a completely bloody lower face in one shot, and barely two rivulets of blood on his chin in the next cut- and then back and forth from there. The continuity person should also refund their fee.
I really wish I could have enjoyed it more, but too many things wrong that can't be ignored end up taking you out of the story - and that is the one sin a filmmaker must not ever commit.