Writer David Croft says that the inspiration for Officer Crabtree, the policeman (played by Arthur Bostrom) who speaks spectacularly bad French, came from Edward Heath, former British Prime Minister, who spoke French with a broad English accent. In real life, Arthur Bostrom speaks French fluently.
There is a restaurant on the Great Square of Kortrijk in Belgium named "Bistro Allo Allo" after the series. The inside of the restaurant is decorated with black and white photos of a few of its most hilarious scenes.
'listen very carefully, I shall say this only once' was never meant to be a catchphrase, it was said once and it got a laugh, so the character of Michelle said it in every episode after. Many famous catchphrase were created by accident.
The original painting of The Fallen Madonna with the Big Boobies, which features in many episodes, was given to production designer Shaun Moore after the series ended in 1992. In April 2007, he auctioned it for £4000 to raise money for the charity the Ace Centre, which helps children with communication problems in Oxford.
Many incorrect explanations have circulated since the start of the series as to what Captain Hans Geering actually shouts when he does the Nazi salute. Sam Kelly has often said that it had cost him a fortune in stamps writing to people to tell them what it actually was, namely '-tler!' which is short for 'Heil Hitler'. Kelly felt that Hans couldn't be bothered saying all of 'Heil Hitler'.
Gorden Kaye was injured in an accident during the British storm of January 25th and 26th 1990, when a plank of wood flew through the windscreen of his car, leaving Gorden Kaye with a scare on his head, which Kaye claimed in a interview that he had no recollection of any details of the accident. Although the scar was noticeable on his head in Series 7 it was not written in the show to explain why Rene had a scar on his head.
Series 5 was commissioned with the intention of syndication in America. As a result, it aired as a single long series of twenty six, twenty five minute shows, from September 1988 - February 1989. The attempt to air the show in America failed but it did get a cult following later on when shown on PBS.
The trivia item below may give away important plot points.
Maria Recaimer is never seen after the episode The Great Un-Escape because Francesca Gonshaw (actress who portrayed her) left the show after three series to play the role of Amanda Parker in the BBC drama series Howards' Way.