Continuity mistake: At the start of the episode, it is clear that the capsule fully rotates and the "contents: 2" sign is not on the capsule. (00:01:05)
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)
Quarantine - S5-E4
Continuity mistake: When Kryten injects the luck virus into Lister's neck, the gun disappears from Kryten's hand between shots. (00:23:25)
Continuity mistake: When the Cat and Lister are playing golf, they stop next to a bed with Marilyn Monroe sitting on it. When the camera angle changes, they begin walking from the other side of the bed. Also Marilyn Monroe is now kneeling. (00:24:20)
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: When the crew are wheeling the Cat in the corridors of Red Dwarf, Kryten is holding onto the Cat's hand. In the next shot he is pushing the stretcher. (00:23:00)
Continuity mistake: Lister's rolling pin is dirty with flour when Christine walks in, but when Lister turns around, it's clean. Then it's dirty two seconds later, and then disappears completely after Lister drops the bowl. (00:26:12)
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)
Rimmerworld - S6-E5
Continuity mistake: During the hold-up scene with the Simulant, in the close-up of her speaking, her face is in darkness. The camera cuts away to Rimmer running for the escape pod, and then back to the Simulant, who is now well lit by a pair of overhead lights. (00:12:10)
Stasis Leak - S2-E4
Continuity mistake: When Lister walks through the Stasis Leak for the first time, his hands are up by his face and his locks are in front of his shoulders. In the next shot from the mirror, his arms are lowered and his locks are only over his right shoulder. (00:09:30)
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)
Stasis Leak - S2-E4
Continuity mistake: When Lister's double comes out of the bathroom, Lister's locks move from in front of his shoulders to behind his neck. (00:25:15)
Stasis Leak - S2-E4
Continuity mistake: When Lister's double says 'You don't look pleased to see me' his locks move from over his shoulder to down his back and they continue switching during the scene. (00:25:30)
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