Out Of Time - S6-E6
Visible crew/equipment: When the Cat becomes visible again after going through an unreality pocket, the shot changes to a wide shot of the crew. A boom mic can be seen to be pulled out of shot at the top of the screen by Kryten's head. (00:11:40)
Revealing mistake: When Legion gets hit, you can see his real face for a second when he adjusts his mask. (00:21:30)
Continuity mistake: In the scene on the Canaries' transport, where they first try to convince Kryten to record the women showering, Kochanski speaks the first line in the scene, but when the shot changes to the wide shot, she isn't there anymore. (Confirmed on the DVD commentary). (00:05:55 - 00:07:20)
The Last Day - S3-E6
Continuity mistake: When Kryten takes the invitation from the skutter, he picks it up with his right hand. In the next shot it has jumped to his left hand. (00:10:20)
Emohawk - Polymorph II - S6-E4
Visible crew/equipment: When Rimmer says the oxy-generation unit is destroyed, a boom mic shadow can be seen on the crate in front of him. (00:09:40)
Out Of Time - S6-E6
Visible crew/equipment: When Kryten bends down to pick up the xrays, a boom mic shadow can be seen on the top of his head. (00:05:00)
Timeslides - S3-E5
Revealing mistake: When Rimmer dies at The End of the episode, a dummy is visible just before the explosion. (00:26:40)
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 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)
Out Of Time - S6-E6
Visible crew/equipment: In the scene just befoe Lister & the Cat go into stasis, a boom mic shadow can be seen moving on the desk in front of Rimmer. (00:12:20)
Continuity mistake: When Rimmer falls asleep whilst Lister is doing the jigsaw, there is a whisky bottle on the table. Later in the episode, when being viewed on the black box, the whiskey bottle is no longer on the table. Lister could not have thrown it away since he left the table to the Hologram Simulation Suite at The End of the scene. (00:10:20 - 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)
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 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)
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 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)
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