The film is set during the years 1917-1918. However, most of the female civilian clothes and hairstyles are contemporary with the late 1920s, particularly the clothes worn by Clara Bow in the home sequences and in the Follies Bergere sequence. Bow's and almost all the other female characters have bobbed hair, common in 1927 but almost non-existent during World War One.
Mary paints the "shooting star" on the left side of Jack's car. Jack immediately drives off to pick up Sylvia. Jack and Sylvia drive past Mary. The "shooting star" is now on the right side of Jack's car.
Mary paints the shooting star on only one side of the car. But a shot or two later of the car from a different angle, where they are standing in front of the car, reveals enough information to show that the shooting star is now painted on both sides of the car.
Jack and David shoot down a German bomber. The soldiers in the just-bombed village come running out and celebrate atop the bomber's wreckage, but by the time it was shot down, the bomber was a good many miles away from the village - too far away for the troops to just run out to its wreckage.
When David says goodbye to his stiff and formal parents and is then greeted affectionately by his dog, as he pets the dog's head, a "treat" can be seen hidden in his hand to make the dogs affectionate.