Revealing mistake: When Mr. Lucas gives Mrs. Slocombe the radio mike, it slips down her dress out of reach; Mr. Harman says "It can't have gone down all that far," and he's right: The short cord of the mike is visible sticking out of the dress for quite some time until Mrs. Slocombe herself pushes the mike down (in the appearance of trying to fish it out).
Are You Being Served? (1972)
1 mistake in It Pays to Advertise - chronological order
Starring: Frank Thornton, John Inman, Mollie Sugden, Wendy Richard
Genres: Comedy
Mr. Humphries: I'm free!
Trivia: The "lift voice" heard during the theme song in each episode is that of Stephanie Gathercole, who played Mr. Rumbold's secretary in the earliest episodes.
Question: If Mrs. Slocombe had squatters in her new flat, why didn't she simply call the police and have them removed?
Answer: That wasn't possible in 1972. Until recently squatting was a civil offence in the UK, not a criminal one, and removing squatters was a complex and time consuming business.