Factual error: Herzog is referred to as "Oberst" (Colonel) both by The Wanderer and in the end credits. But both he and his men wear SS uniforms and insignia, where standard military titles were not used. Herzog should have been called the SS equivalent "Standartenführer".
After Martin cuts his arm off, there are several scenes where you can see the bulge of the actors real arm under his jacket. This is most noticeable when he is running through the birch wood, and when rooting through the ruins of the burned cabin.