When William Potts (Will Hay) first meets his students, he does a roll-call. One of them answers to the name "Schicklgruber", causing Potts unease, and glancing up at the portrait of Adolf Hitler. Hitler's father was born Alois Schicklgruber, and later changed his name in order to reflect that of his stepfather.
On the film set during the classroom scenes, Barry Morse described Will Hay as displaying no sense of humor in the slightest. According to Morse, the comedian spent time in a chair with a blanket across his lap in-between takes.
The film was released in a heavily edited version for years and it seemed was the only one available. A few years ago, some of the missing footage was added to the recent DVD/Blu Ray release and now the film can be enjoyed properly.
At the beginning of the film, Hay is wearing a protective cover over his right index finger. This disappears after about 20 minutes.