An episode is kept on standby by the BBC for use as an emergency back-up program, to be broadcast if a major technical problem prevents normal programs being shown. This came to light on June 20, 2000 when the Six O'Clock News (1984) was interrupted by a power failure at the BBC, and an episode of this show was transmitted in its place.
Despite always referring to Sergeant Wilson as Uncle Arthur, it was finally confirmed that Private Pike is the biological son of Sergeant Wilson, when, on the very last day of taping, Ian Lavender asked co-writer and producer David Croft: "Is he [Wilson] my father?" To which a seemingly bemused Croft replied, "Of course he is!"
David Croft considered the filming of season nine to be "an ordeal" due to the frailty of the cast:
John Le Mesurier looked thin and ill, as he was suffering from liver failure brought on by excessive drinking; Arthur Lowe's trouble remembering his lines was getting worse, to the point where Captain Mainwaring's office drawer was constantly full of bits of script for him to read; and Arnold Ridley ripped a cartilage in his leg meaning he had to be ferried by limo to and from the studio.
When an episode of the show was shown to members of the public to gauge audience reaction prior to broadcast of the first season, the majority thought it was very poor. The production team put the report containing the negative comments at the bottom of David Croft's in-tray. He only saw it several months later, after the series had been broadcast to great acclaim.
Bill Pertwee used to warm up the audience before each recording. He was the only one of the main cast with experience as a stand-up, and had also been warm-up man before other BBC shows.