Episode #3.5 - S3-E6
Continuity mistake: Sidney is attending a pre-wedding dance in the camp he is visiting wearing a light colored shirt. When he leaves the dance floor to chat with other attendees, he is now wearing a green sweater over his shirt.
Episode #1.3 - S1-E3
Other mistake: The publican asks for payment for some drinks, saying "One and six, please", meaning one shilling and sixpence. The subtitles say "One-o-six, please."
Episode #7.5 - S7-E5
Trivia: The Matron is called Fletcher. Louise Fletcher played the chief nurse (and a similar character) in "One Flew Over the Cuckoo's Nest."