Audio problem: When Lister and Rimmer see Cat just after Holly explains how he evolved, Rimmer runs at Cat screaming before he passes through him and we hear a crash off screen to indicate Rimmer has just run in to something. He is a hologram and is not solid, so no sound should be heard. [The original version did not have this mistake. The sound effect was added for the now defunct Remastered series.] (00:27:10)
Audio problem: In Rimmer's future echo he says, "You're space crazy", but in the real conversation with Lister, he actually says, "You are space crazy". (00:15:20 - 00:16:15)
Audio problem: During the conversation in which Holly wants to prove he has an IQ of 6000 (while Lister and the Cat are scrubbing the floor), there is a brief moment where you can see the TV Holly is on (at an angle). You can hear sound coming from him, but his lips aren't moving. (00:16:55)
Audio problem: When Kryten starts looking over Lister's bunk trying to find the Polymorph, posing as the boxers, the boxers, and therefore the Polymorph, are visible on the bunk. The sound of the Polymorph transforming is heard, indicating the Polymorph has changed form, but the boxers remain there, without any transformation. It is not until a few shots after that the Polymorph has appeared to have changed form. (00:10:00)
Timeslides - S3-E5
Audio problem: In the photo of 'Smeg and the Heads' you can see that the drummer frantically plays the cymbals, but no sound comes from them. (00:11:40)
The Last Day - S3-E6
Audio problem: When Lister tries to shoot Hudzen, Hudzen grabs Lister and throws him, but a punch sound effect can be heard, despite no punch being made. (00:26:15)
Audio problem: When Kryten says 'Excuse me, could I just distract you for a brief second?' his lips are out of sync with the dialogue and continue to move after he has finished speaking. (00:23:35)
Quarantine - S5-E4
Audio problem: When Dr. Lanstrom says 'Life without pain has no meaning' Kryten begins to speak but no words are heard before the shot changes. (00:07:10)
Quarantine - S5-E4
Audio problem: When Dr. Lanstrom says hello into the walkie talkie, her lips do not move. (00:08:40)
Quarantine - S5-E4
Audio problem: When Rimmer is talking to Lister, Cat and Kryten in the dress, the Cat says "We thought you'd gone nuts" and the shot cuts to Rimmer where the Cat then says "We were trying to heal you." When the shot is on Rimmer, the Cat's reflection can be seen in the mirror and his mouth doesn't move with the line. (00:21:05)
Audio problem: When the high Lister plays the harp, his fingers are out of sync to what is being played. (00:11:30)
Audio problem: When the high Kryten picks up the bomb, the high Cat can be seen to start speaking but no sound is heard. In the next shot, the high Cat is then smiling. (00:13:30)
Audio problem: During the munchkin song, near The End, one of the lines of the song is "then he just might come round for dinner" - however Rimmer mouths "he might just come round for dinner" instead - swapping the words "might" and "just" (00:26:00)
Audio problem: When they are chasing Jesus through the market, Lister's mouth is out of sync when he's shouting. (00:26:15)
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