Continuity mistake: When the Cat asks if fish swim south for the winter, Kryten is looking at him. In the next shot, as Kryten answers, Kryten is looking up and away from the Cat. (00:02:05)
Continuity mistake: When the Cat is holding up the haddock, Kryten is stood in front of him holding out the scanner. In the next shot, Kryten has vanished, then reappears. (00:03:00)
Continuity mistake: When the Cat is holding up the haddock, going through the people who have commited suicide, the shot changes and the haddock disappeares from his hand. Also after the shot changes, the Cat is then pointing at Kryten and smiling. (00:03:25)
Continuity mistake: After the Cat starts to cry, he is looking at Kryten and Lister. In the next shot he is looking down. (00:04:50)
Continuity mistake: When the crew are looking at the radar, Lister's locks are in front of his shoulder on the radar cam, but behind his back in all other shots. (00:05:50)
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)
Continuity mistake: When the crew almost kill themselves, Kryten is holding the harpoon gun to his head. The point of the spear is missing but in the next shot it has reappeared. (00:23:30)
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