When Boeldieu is dead, Rauffenstein wants to close his eyes with his hand. When the hand of Rauffenstein gets close to Boeldieu, his eye moves.
However, watching the scene image by image there does not seem to be any eye movement not made by the hand.
When Lt. Maréchal is climbing down the rope from the watchtower the wooden window shutters can be seen closing above him even though there shouldn't be anyone there to close them.
As the WWI German soldiers are celebrating a French fort's capture, the map on the wall of the officers club is clearly an inter-war (1919-1938) map of Germany.