When the sign at Monique's is splattered by mud the N is only partially covered, but in the next shot the N is completely covered.
After the motorcycle with a side car drops off Lurk, it sprays him with mud all over. Next shot the amount of mud on his uniform is less and his face is clean.
Near the beginning Groping states that the Hun are at the gates AGAIN, the film is set in the First World War so it is the first time Britain was at war with Germany.