Continuity mistake: When the Captain is making his speech for George McIntyre, he takes his hand out of his pocket and touches his glass. In the next shot, his hand is back in his pocket again. (00:10:35)
Continuity mistake: Just before Rimmer and Lister drink the hooch, Lister's locks are behind his back, then one of the locks moves to in front of his left shoulder during a brief shot of Rimmer. (00:13:30)
Out Of Time - S6-E6
Continuity mistake: When Rimmer picks up the bazookoid at The End of the episode and runs into the engine room, the gun is pointing up. In the next shot from inside the engine room, it is pointing down. (00:27:10)
Continuity mistake: During the Higher Cat and Rimmer's dance when Kryten says 'and agony in torment' his arms are by his sides. In the next shot, his right arm is raised. (00:11:40)
Continuity mistake: When the Cat dances at the disco, he jumps up and grabs the mirror ball with both hands. In the next shot he is only holding it by one arm. (00:20:25)
Stasis Leak - S2-E4
Continuity mistake: When Lister first walks through the Stasis Leak, his locks are over his left shoulder, then in the bathroom they are over both shoulders. (00:09:30)
Continuity mistake: A door has appeared in the main living area of Starbug that was not there in previous episodes. (00:01:50)
Out Of Time - S6-E6
Continuity mistake: When the crew fire at their future selves, Lister says 'locking on, firing'. His locks are behind his back but in the next shot they are in front of his left shoulder. (00:26:10)
Terrorform - S5-E3
Continuity mistake: Just after one of the hooded legions reads from the scroll, he manages to turn around and face the opposite direction in one camera cut. (00:10:45)
Continuity mistake: Lister says his ID code is Lister-D-00169, yet in Furture Echoes he gave it as RD-52169. (00:14:55)
The Last Day - S3-E6
Continuity mistake: When Kryten throws away the breakfast, Lister's locks move from behind his shoulder to in front of it in a single cut. (00:01:55)
Continuity mistake: When Lister is changing near the start of the episode, there are no stickers on his locker. When he leaves the room, they appear. (00:03:55 - 00:05:10)
Continuity mistake: After Rimmer and Nirvanah have sex, as they're getting out of bed, Nirvanah ties her robe twice. In the next shot as she's standing, the robe is open again. (00:14:00)
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