After PFC Georgie Warren walks away after greeting two buddies from the military school while at camp, a clear shadow of the boom microphone is visible on the ground.
In the opening sequence in the trenches, Capt Riker shoots an enemy soldier with his service pistol, a Model 1911 automatic. He then uses his thumb to re-cock the weapon. This is unnecessary since the 1911 automatically re-cocks itself after firing.