To the modern discerning eye, the use of miniatures is apparent in some scenes. If one looks very closely at the first scene, ambulance trucks driving up a winding mountain road will be seen to be well crafted miniatures.
A night attack is shown. During World War I there was very little flying at night and the night attacks that did occur were limited to big cities. It was almost impossible for a plane to attack specific targets in a large city, so effectively attacking people on a road in the dark was not possible, and did not happen.