Revealing mistakes: The Texas flag is displayed upside down.
Anachronisms: Any Fokker Dr.1 triplanes available just after WWI would have the original rotary engine, rather than a radial engine. The difference is that the rotary engine spins along with the propeller, and a radial engine doesn't. The Fokker in the 59th minute clearly has a radial engine.
Factual errors: Towards the end of the movie, Bill fires three shots from a double-barreled shotgun without reloading.
Audio/visual unsynchronized: At about 7:25 into the movie, we see a bucolic farmyard scene, with a group of white ducks waddling by...yet we hear sound effects of Canada Geese.