When going to their first battle, while the young soldier is talking to Kat, the young soldier's bag switches from being across his chest with his hands by his side to his bag not being there and his right arm holding his scarf between shots.
When the young recruits go out on their first patrol, to add to the barb wire entanglement; the veteran uses a mallet to drive the post into the ground. While the movie went to the trouble to have the right kind of post they used it completely wrong. That post was developed by the Germans to allow them to put up barbed wire much more quietly then the Allies. The bottom portion of each post is twisted into an auger; this allowed the soldiers to simply put the post on the ground; put a rod through one of the holes in the post and screw it into the ground. This was one of innovations that the Allies copied. Both sides had listening posts near the wire on their sides to listen for infiltrators and wire crews; once detected they would be cut to pieces by machines gun or mortar fire.
As men are seen being shot by a German machine gun, they are seen just falling down dead. In reality, the power from such weapons was so great that the fire blew large chunks of the target's body away. By example, a single volley at Passchendale ripped both my grandfather's left leg and arm completely off, although, miraculously, he did survive.