Continuity mistake: When Lister takes the milk from his locker, keep an eye on his duvet. In the next shot when he pours the milk, it has moved and is hanging down from his bunk. The red mug on the table also moves from near the magazines to near the ashtray on the other side of the table. (00:14:35)
Deliberate mistake: In the first few series, it is suggested Lister and Kochanski barely know each other. In 'Balance of Power' Holly says that Lister has only ever spoken 173 words to her. However, by series 4 Kochanski is referred to as Lister's ex-girlfriend with whom he shared a relationship. In the series 4 documentary, Doug Naylor explains that Lister's attitude towards Kochanski was immature in the first series which is why they changed his back story from wanting to be with Kochanski to actually having been with her by series 4.
Other mistake: When Lister (in Rimmer's body) pleads the Cat to lend him his body, he says "how else can I pilot White Midget?" In the next scene, the Blue Midget is being piloted, and White Midget was originally abandoned for Starbug. (This mistake was admitted by the crew). (00:21:45)