In the scene where Tom and Molly meet at sunrise, the shadows of the trees look like it's mid-day.
The famous song "My Buddy" is played in this film set in World War 1 but it wasn't written till 1922, four years after the end of the war.
In one shot of the horses charging forward in the big battle sequence near the end, a clear shadow of the camera platform and equipment is seen in the ground.