Factual error: Some of the German planes that appear in the film are actually just British-made Tiger Moths painted in German airforce markings. The Moth was a type that was only built some years after the end of the First World War.
Factual error: 1. When Stachel first arrives at the squadron, they already have Fokker DVII's as part of their complement. This machine did not come into service until after Richthofen was killed, yet he makes a brief appearance in the scene where Stachel is shot down. 2. The German markings are of the older style (prior to the introduction of the DVII). From early 1918 the national insignia is supposed to be simplified, like a plus sign, without the flared look of the Maltese cross.