Some German soldiers have a skull painted on their helmet. This specific type of skull decal was used by a Finnish army unit (1st battalion, infantry regiment 46) in the continuation war 1941-1944. A famous colorized photo of three Finnish soldiers in a trench wearing this sort helmet decal of is often incorrectly associated with Germans or the SS.
Herold committed his war crimes in the northwestern part of Germany (Papenburg, Leer, Aurich). A very flat landscape, small towns with mostly brick buildings. The filming locations are obviously in southeastern Germany, around Goerlitz.
After the execution when the dead bodies are being covered with lime, the officer is very careless and a whole cloud of the dust is floating in the air. Lime is a very dangerous corrosive agent which react with water violently and can instantly blind a person if gets into the eye. The execution squad must be aware of this, yet none steps back.
When the first artillery shell strikes the camp, everybody just stands dumbfounded, looking at the result. In reality these crusty, seasoned front veterans would've hit the deck instinctively when they heard the hiss and disperse.