Continuity mistake: When Kryten says about the cryptic clue, his arms are by his sides. In the next shot, they are outstretched. (00:14:15)
Terrorform - S5-E3
Continuity mistake: When Rimmer gets his robe torn off, he is looking forwards. In the next shot he is looking down. (00:11:00)
Continuity mistake: When The Inquisitor jumps Kryten from behind, he used both hands. In the next shot he is only using one hand to hold him. (00:14:05)
Timeslides - S3-E5
Continuity mistake: During the golf game, Lister's locks move between shots throughout the scene. (00:01:20 - 00:02:20)
Confidence and Paranoia - S1-E5
Continuity mistake: When confidence explodes outside the ship, a helmet appears on the walkway which was not there earlier in the scene. (00:26:50)
Continuity mistake: When the low Kryten takes the spinal implant from low Lister, he uses his right hand. In the next shot, the implant has switched hands as Kryten uses his right hand to lift up Lister's head. (00:16:40)
Continuity mistake: When Ace Rimmer is talking to the Cat as a priest, the Cat has the pipe in his mouth in one shot, then he is holding it in front of him in the next. (00:03:45)
Continuity mistake: Just before Lister says 'I'm going to give him Lisa Yates' he is looking forwards. When the camera angle changes he is looking at the Cat. (00:18:15)
Continuity mistake: After the Cat says about mooning out of the windows when Starbug gets hit, Kochanski falls back on her chair with her arms outstretched. In the next shot she is holding onto the monitor again. (00:25:00)
Continuity mistake: During the battle, the Dalai Lama can be seen running through the field after he is killed. (00:23:05)
Continuity mistake: Rodon is revealed to be the Cat's older brother, and the rebelling cats refer to the Red Dwarf itself as the ship of their birth, but in Psirens, it was revealed that the crew spent 200 years in deep sleep while tracking Red Dwarf. This appears to have been forgotten.
Continuity mistake: When the Cat is eating the food set out by Lister, there is a cloth on the table. When Lister is asking where the other kitties are, the cloth is shown near the centre of the table. Rimmer then says he wants it off the ship, and the cloth is suddenly further to the right of the table. (00:27:45)
Continuity mistake: When Lister is revising for the exam, he opens a can of beer which sprays foam onto the table, and onto his cigarettes, when he opens it. A few seconds later, the sprayed foam disappears from the table. (00:19:30)
Continuity mistake: When Rimmer is talking to Lister before the exam and says they are friends, Lister replies "When?" Lister has a can of beer on the bunk, with the label facing the camera. Two shots after, the label is suddenly facing away from the camera. A couple of shots after that, the label is suddenly facing the camera again. (00:23:15)
Confidence and Paranoia - S1-E5
Continuity mistake: When Confidence is telling Lister that his song was the greatest love song ever, Lister has his right hand on his lap, but in the next shot, his right hand is suddenly on the guitar strings. (00:19:35)
Continuity mistake: When Lister is questioning how they can remake Casablanca, he is holding the video tape, but in the next shot, the tape has disappeared from his hand and is touching the control panel. (00:04:40)
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