Continuity mistake: When Kryten decides to be a mechanoid again, Lister gets up and grabs his jacket and swings it around his shoulders. The camera cuts to Kryten for a second then back to Lister, who now has his jacket on fully. The amount of time the camera was away from Lister would make this impossible for him to put the jacket on that quickly. (00:22:15)
Visible crew/equipment: When Lister puts his mutton vindaloo on the DNA modifier, the pole used to make the vindaloo float can be seen when the beam is cast on the dish. (00:22:55)
Revealing mistake: When it is revealed that the DNA modifier has made Lister smaller, Rimmer, Cat and Kryten all have shadows cast on the floor, but Lister does not. (00:25:25)
Continuity mistake: When Lister has been made smaller, one shot shows him holding the bazooka, but the next shot shows him with his hand lowered. (00:25:30)
Continuity mistake: When Lister sarcastically thanks the Cat for visiting him, Lister looks forwards, but in the next shot is looking at the Cat. (00:03:35)
Revealing mistake: One of the escort boots passes through a wall as it goes round a corner. (00:10:10)
Visible crew/equipment: When the crew are standing before the Judgement computer (when Lister is worrying that he will be sent to prison) if you look above Lister's head you can see a microphone bob up and down into shot. (00:11:10)
Factual error: The justice computer states that Rimmer is guilty of 1167 counts of 2nd degree murder, each carrying a sentence of 8 years giving a total of 9328 years. This is equivalent to 1166 counts. (00:14:00)
Answer: The cello is a large four-stringed instrument, which, when it is played, stands vertically on the floor between the player's legs (assuming they are seated). If it is to grow as large as the other instuments mentioned will, it would require a rather unseemly lack of femininity to be able to encompass it with the legs.
Rooster of Doom