Continuity mistake: When the German colonel crash lands in the Channel, he first hangs directly under his upside-down plane before he has to let go, and the plane zooms in a straight line away from him. But as he resurfaces in the foreground, the plane comes in from the background's left before landing in the water.
Continuity mistake: The number of tail fins on the "American" aircraft changes from two to three depending on the shot.
Continuity mistake: In some scenes the "Antoinette" flown by the British flyer has authentic, thin "wing warping" wings. In other scenes it has thick modern glider wings with ailerons. This was done because the authentic machine wasn't very airworthy and was modified during the shooting.
Continuity mistake: When Sir Percy attempts to spy the other fliers from the hangar roof, he uses a ladder to get to the top. But when Dubois startles him and he slides off the roof, the ladder on the roof slope is gone.
Continuity mistake: The Avro Triplane goes back and forth between using the authentic four-blade metal-and plywood propeller from the era and a two-blade massive wood propeller. The reason is, the producers originally tried to use the historic designs as much as possible, but had to change some things in the course of the shooting because the originals proved to be not airworthy enough.