Deliberate mistake: When Schultz drives off with the motorcycle leaving the sidecar behind, you can see that the sidecar has been propped up. It has to be, or it would fall over. Sidecars, bringing only one wheel to the party themselves, can't stand up on their own.
Trivia: A sinister aspect of an otherwise lightheated comedy, but the fact is that Hogan and his men are war criminals. They engage in combat activities behind enemy lines when not in uniform, and worse, while wearing enemy uniforms. The Germans tried that during the Battle of the Bulge and those arrested were shot.