Continuity mistake: When the crew are looking at the radar, Lister is looking at the crew in one shot then at the radar in the next. (00:06:10)
Continuity mistake: When the crew run down the alley after the chase, the order that they go in changes between Starbug and the hallucination. (00:22:40)
Visible crew/equipment: At The End of the episode when Lister makes his speech, the first shot shows a close-up of his face, then it shows a wide shot. A boom mic is pulled out of shot at the top of the screen. (00:25:50)
Continuity mistake: When Lister is explaining the ending of the movie, he says "It's about a dude who sacrifices his life for love" whilst Rimmer looks at him, but in the next shot, Rimmer is suddenly looking forwards before turning back to Lister saying "as if." (00:02:55)
Continuity mistake: When Kryten tells Rimmer he doesn't have the brain that can accept an implant, he says "No" and begins walking around the table. Kryten has his hands raised with his right hand slightly lower than the left, but in the next shot, both hands are suddenly level with each other. (00:22:05)
Terrorform - S5-E3
Continuity mistake: When Kryten cuts off his hand, all of the fingers on the hand are straight and level with each other, but when he goes to attach his eye to one of the fingers, the middle finger is suddenly raised. (00:02:35)
Continuity mistake: When Starbug bursts out of Red Dwarf, the shot from behind shows Starbug spinning in circles, but the shot from in front shows Starbug flying normally. (00:04:00)
Quarantine - S5-E4
Audio problem: When Rimmer is talking to Lister, Cat and Kryten in the dress, the Cat says "We thought you'd gone nuts" and the shot cuts to Rimmer where the Cat then says "We were trying to heal you." When the shot is on Rimmer, the Cat's reflection can be seen in the mirror and his mouth doesn't move with the line. (00:21:05)
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