Goofs

In a later scene, a postal envelope shows a Connecticut ZIP Code. The ZIP Code system wasn't developed until 1963.

During Basic Training and their deployment to France the members of the 102nd Infantry Regiment (United States) 26th (Yankee) Division are wearing the shoulder sleeve insignia with a Green Diamond with blue "YD" monogram. The first shoulder sleeve insignia was not authorized by the US Army, due to a request by General John J. Pershing, until October 1918. The unit was in Basic Training in 1917 and the Battle of Saint-Mihiel where the 26th Infantry was stationed near Seicheprey, was fought from 12-15 September 1918. The unit patch would not have yet been created and would not have been part of their uniforms.

In one of the later scenes, they show an envelope that is addressed to a town in Connecticut. In that address, it shows a 5-digit ZIP Code. However, the movie is set during World War I, but ZIP Codes weren't used until 1963.

The rifles shown being used by the US troops in the movie appear to be 1903A3 models which were not produced until about 1940. The correct rifles used by US troops in WWI were the original 1903 Springfield from which the 1903A3 was later developed or the 1917 Enfield rifle.