Continuity mistake: At The End of "Nanarchy", Kochanski's hair is brown. However, throughout series 8, her hair is blonde. And with everything going on in "Nanarchy" there would have been nowhere near enough time for her to dye it.
Continuity mistake: When Lister is lying on the top bunk talking to Rimmer about the 83 year old dad, he says "he'd probably pretend to be dead" as he puts is left hand on the side of his face. The camera cuts to Rimmer then back to Lister again, as he puts his left hand on the side of his face again. (00:01:55)
Continuity mistake: At The End of "Nanarchy" Starbug 1 flew underneath Starbug 2 at The End of the episode, yet in this episode when the scene is repeated, the ship flies around Starbug 1 instead. (00:05:50)
Continuity mistake: When Starbug crashes through a vent, Lister leans to his far right. In the next shot, he is leaning to his left. (00:09:20)
Visible crew/equipment: Just before Starbug crashes and Kryten says they will have sandwiches for lunch, a boom mic can briefly be seen above his head. (00:09:45)
Visible crew/equipment: During the scene when Starbug crashes, the camera then does a barrel roll and you can see wooden roof beams of the set and the stage lighting. (00:09:55)
Continuity mistake: When Lister goes to hug Selby and Chen, his locks are over his right shoulder. In the next shot they are behind his back. (00:10:40)
Continuity mistake: When Thornton places the bracelet on Lister's arm, Lister's arm is at a straight angle, but in the next shot, his arm is at a rotated angle. (00:12:15)
Continuity mistake: The view of space outside the window in Rimmer and Lister's bunk shows a completely still background, but every other view of space through a window shows the ship moving. (00:14:10)
Revealing mistake: When Kryten's hand inflates and flies away, his forearm bends in the middle. (00:06:40)
Continuity mistake: When Kryten's head falls off it bounces with no velocity, yet in the next shot it is quickly rolling out of the door. (00:06:55)
Continuity mistake: When Kryten tells Kochanski he doesn't have a penis, he turns away from her. In the next shot you can still see Kryten on the right of the screen as he turns away from her again. (00:07:20)
Continuity mistake: When Rimmer shows Lister the luck virus and sexual magnetism virus, there is less than half of the liquid shown in the test tube for the sexual magnetism, but when Rimmer is about to go to Hollister's dinner later on, there is more liquid in the test tube. There was also only one test tube of sexual magnetism for Rimmer to use. (00:12:15 - 00:18:10)
Continuity mistake: In the bathroom when Kryten says he does not want his corrupted files repaired, he holds out his arms. In the next shot when the guards stun him, they are by his side. (00:15:00)
Continuity mistake: Just after Kochanski jumps on Lister, she stands up and says 'I don't know what got into me' with her hand on her head. In the next shot, her hand is by her side. (00:16:35)
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