Emohawk - Polymorph II - S6-E4
Revealing mistake: When the Gelfs release the Emohawk, it is thrown into the air and it flies away. However, if you look at the third Gelf you can see the shadow of the Emohawk puppet as it falls to the floor. (00:17:30)
Terrorform - S5-E3
Continuity mistake: The cutting torch Kryten uses to cut his hand off appears from nowhere. (00:02:20)
The Last Day - S3-E6
Continuity mistake: When Kryten is packing his heads away at the point where he says 'how would the manufacturers sell their latest model?' he is looking forwards. The camera changes angles and he is looking down. (00:04:00)
Continuity mistake: Just before Lister cuts himself shaving, he is shaving away from himself. The camera changes and he is shaving in the oposite direction. (00:13:00)
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)
Revealing mistake: During the scene in the space station's dining room, when Craig Charles is making a speech explaining that they should escape, he stands up and pours himself a glass of Bucks Fizz. Craig fills the glass too soon (half way through the speach) and must realise, as he pours the drink back into the pitcher, and then begins filling his glass again. (00:20:20)
Visible crew/equipment: When Rimmer says that Kennedy was a fine man, a boom mic can be seen at the top of the screen. (00:20:22 - 00:21:17)
Continuity mistake: During the Cat's dance, he taps his feet and tilts his head back, which Blue Midget copies. In the next shot Blue Midget is looking downwards and then proceeds to do the same dance it just did in the previous shot. (00:10:00)
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)
Emohawk - Polymorph II - S6-E4
Visible crew/equipment: When Rimmer says 'details halibut breath' a boom mic can be seen to Rimmer's left. (00:07:30)
Visible crew/equipment: When Lister washes his face in his sleeping quarters, Rimmer is seen off set in the reflection in the fish tank walking past. You can see his uniform and can just make out the H on his forehead. (00:04:40)
Continuity mistake: When Lister first sees Kochanski his locks are on top of his left shoulder. In the next shot they are gone, then back again when he drops the bowl. (00:26:15)
Confidence and Paranoia - S1-E5
Continuity mistake: When Lister is watching the film at the start of the episode, he says 'would you let me watch the film' to Holly. His arm is gesturing to Holly, but in the next shot he is picking up chips from his lap. (00:02:50)
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