Continuity mistake: Watch the cat priest's black hand. It starts off normal, then it turns crusty and white. Just before he dies, his hand is normal again. (00:25:55)
Continuity mistake: After Rimmer and Lister argue about the pod, Rimmer walks off and Lister steps into the observation room. As Lister steps in, his locks are over his left shoulder, then in the next shot they are over his right shoulder. (00:14:05)
Continuity mistake: When the cat priest dies, the hat he is wearing falls onto the bed above his head. When the shot changes the hat is gone. (00:26:35)
Continuity mistake: When Rimmer says he wants the 'aliens' to give him a real body, his arms are outstretched. In the next shot they are folded. (00:17:20)
Continuity mistake: When the Cat leaves Lister's quarters after showing him the cat book, one of Lister's locks is hanging over his right shoulder. In the next shot it is gone. (00:11:40)
Continuity mistake: When Rimmer first realises that his files are unflattering, the screen first from the right on the computer bank shows writing. But a change of view later, Holly is on the same screen. He does not have time to move.
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