The platoon and their prisoners march past the same short stretch of warehouse frontage several times.
Conditions on u-boats were notoriously dirty, and German submariners habitually grew beards at sea; furthermore, the Captain and his crew have spent two days marooned in a lifeboat. However, their uniforms are clean and tidy and they are neatly shaven.
When Wilson and Pike are in the office "arming" the grenades, a microphone shadow may be briefly observed on the right wall.