Continuity mistake: When the Nazi commander throws the crocodile at Ace, it changes size between shots. As he throws it, it is small and easy to throw, yet in the next shot it reveals it is taller than Ace. (00:01:00)
Continuity mistake: Lister screws in Kryten's replacement head (the one without the 'guilt chip') in exactly the SAME direction that he unscrewed the original head (to be exact - clockwise) (00:09:50)
Continuity mistake: When the tent disappears, Lister's locks are over his right shoulder. In the next shot they are over both shoulders. (00:10:00)
Continuity mistake: During Ace Rimmer's funeral, the blow up doll is not visible earlier in the scene next to the Cat, but then appears from nowhere. (00:24:50 - 00:25:40)
Continuity mistake: When Kochanski puts the cat in the disintegrator, it changes the way it's facing between shots and again when she takes it out. (00:11:19)
Continuity mistake: Able's head bounces off the simulant and lands behind him, yet when Lister sends the gelf and simulant back to their ship, the head is next to him on the floor. (00:20:10)
Continuity mistake: When the ducts are being backwashed, Lister's dreadlocks are on his right shoulder. But when the shot changes and he says "I hate this. I really hate this.", his locks are on his left shoulder. Then the shot changes again and they're back on his right shoulder. (00:23:53)
Continuity mistake: When the simulant drinks his drink, he lifts the cup up to drink, yet in the next shot he lifts the cup up again, repeating the same action twice between shots. (00:13:50)
Continuity mistake: When Lister claims his 'prize' the king's hands are on his lap. In the next shot his right hand is clutching the helmet. (00:09:05)
Continuity mistake: When Lister unscrews Kryten's head, the plastic bag on the table moves between shots. (00:11:30)
Continuity mistake: A door has appeared in the main living area of Starbug that was not there in previous episodes. (00:01:50)
Continuity mistake: When Lister drags Kryten through a doorway by his groinal attachment, he is using one hand. In the next shot he is using both hands. (00:12:05)
Continuity mistake: When Lister picks up the camera at the start of the episode, he stands up and turns around. In the next shot, from the view point of the camera in his hand, the shot is still rotating as if he had just picked the camera up. (00:00:15)
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