Terrorform - S5-E3
Continuity mistake: When Lister and the Cat type into the computer, the words are out of synch with the key tapping. (00:05:15)
Continuity mistake: When Lister says 'We don't exist here anymore,' the way Kryten is facing changes between cuts. (00:15:10)
Continuity mistake: When the Cat says, "So what do we do with them?" Kryten disappears from Lister's left between camera shots. (00:17:30)
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)
Quarantine - S5-E4
Continuity mistake: When Rimmer is looking at the crew through the viewscreen in Quarantine, the reflection of the crew in the glass changes between shots. (00:21:20)
Continuity mistake: When Starbug jolts for the first time, Rimmer is looking to his right. The camera cuts and he is looking forwards. (00:03:30)
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)
Continuity mistake: After the Cat incapacitates Lister, the Cat complains about his collar being untidy, then steps aside. The next shot shows Lister stood on his own and the Cat is not visible at all. There was no time for the Cat to walk that fast between shots. (00:23:20)
Terrorform - S5-E3
Continuity mistake: After the crew fire at the Self-loathing Beast and the room fills with dust, the Cat's left hand is up in the air. In the next shot he is holding the bazooka with both hands. (00:17:00)
Continuity mistake: When Lister is choking the Cat, he says 'give me a break, Rimmer'; at this point Rimmer is looking at the Cat and Lister, yet in the next shot he is looking at Kryten. (00:22:50)
Continuity mistake: The bottle of chloroform Kryten uses to take Lister by surprise appears from nowhere. (00:23:30)
Continuity mistake: After the future Kryten cuts off The Inquisitor's hand with the chainsaw, he kicks the glove which lands about 7 feet away from Lister. In the next shot Lister simply bends down and picks the glove up from in front of him. (00:13:45)
Continuity mistake: When Lister, the Cat and their higher selves are walking down the corridor, the way Lister is facing changes between shots throughout the scene. (00:09:30)
Quarantine - S5-E4
Continuity mistake: When Lister gets the second luck virus injection, his locks move from in front of his shoulder to behind his back. (00:23:25)
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