Kochanski mentions being brought up in the Gorbals, the trendiest part of Glasgow. This is an in-joke because around the 1980s, the Gorbals was considered one of the most dangerous place in Scotland because of its slums, street gangs and violence, and was the setting for the famous novel "No Mean City". Today, much of it has been demolished. This version of Kochanski does not have a trace of a Scottish accent, but speaks a form of Estuary English.
This was the last episode written for the seventh season. The show's budget had been stretched by the end of the season so a 'bottle episode' with limited sets and effects was needed to replace a more expensive one. The original episode was that Cat has to have sex or he would die so the Dwarfers find a planet of female Cats. According to Danny John-Jules, the rest of the cast also did not like that the episode would have focused primarily on his character.
In Series VII's bonus features, Craig Charles mentions one word has been dubbed over in the scene where he tells his story about him developing claustrophobia, as it turns out this word was left un-dubbed on the first VHS release of Series VII and is, in fact, 'Fuck'.
Firefighters with fire hoses supplied the flush of water that sends the Dwarfers through the ducts.
When the scene where Kochanski is being driven crazy by the squeaks and noises from the sewage pipes was filmed, Chloë Annett accidentally banged her arm when she hit the wall she was supposed to hit with the spanner.