Continuity mistake: When Legion puts his mask back on, just as he says "Kryten knows", the mask is not properly fixed on, leaving his chin exposed, but when the camera is on him next, the mask is suddenly fixed into place. (00:21:35)
Gunmen of the Apocalypse - S6-E3
Continuity mistake: When Lister tells Rimmer that the escape pod is not an option, Lister is looking at Rimmer, but in the next shot, he is looking down at Kryten. (00:12:20)
Continuity mistake: When Lister is explaining the ending of the movie, he says "It's about a dude who sacrifices his life for love" whilst Rimmer looks at him, but in the next shot, Rimmer is suddenly looking forwards before turning back to Lister saying "as if." (00:02:55)
Continuity mistake: When Kryten tells Rimmer he doesn't have the brain that can accept an implant, he says "No" and begins walking around the table. Kryten has his hands raised with his right hand slightly lower than the left, but in the next shot, both hands are suddenly level with each other. (00:22:05)
Terrorform - S5-E3
Continuity mistake: When Kryten cuts off his hand, all of the fingers on the hand are straight and level with each other, but when he goes to attach his eye to one of the fingers, the middle finger is suddenly raised. (00:02:35)
Continuity mistake: When Starbug bursts out of Red Dwarf, the shot from behind shows Starbug spinning in circles, but the shot from in front shows Starbug flying normally. (00:04:00)
Continuity mistake: When Camille asks Kryten if they could make it, Kryten puts his glass down on the table. In the next shot, it is suddenly back in his hand, being put back down again. (00:22:35)
Continuity mistake: Lister enters with a tray with some food on to give to Kryten. The position of the tray changes position between shots. (00:10:10)
Continuity mistake: When Lister has been made smaller, one shot shows him holding the bazooka, but the next shot shows him with his hand lowered. (00:25:30)
Continuity mistake: When Lister sarcastically thanks the Cat for visiting him, Lister looks forwards, but in the next shot is looking at the Cat. (00:03:35)
Continuity mistake: When the group are about to open the door with the heat seeking missiles inside and the Polymorph sneaks up behind them, Lister is standing at the front of the group, Cat and Kryten are behind Lister and Rimmer is standing at the back, behind all three. In the next shot, as the missiles exit the door, Rimmer is now suddenly standing front of Cat. (00:24:40)
Continuity mistake: When Lister (in Rimmer's body), Cat and Kryten are chasing Rimmer in Blue Midget, the exterior shot shows all three sitting in one row. From the interior, Cat is sitting in front of Lister and Kryten, and Lister and Kryten are sitting behind Cat. (00:22:40)
Continuity mistake: When Rimmer (in Lister's body), is driving Starbug through the moon, the others are following in Blue Midget. One shot shows Blue Midget directly behind Starbug, but another shot shows Blue Midget much further to the right. (00:23:10)
Timeslides - S3-E5
Continuity mistake: When Kryten notices the photo of the bike in the countryside is moving, the peg attached to it is near the middle, along the top, but in the shot from behind, the peg is much closer to the right. The same goes for the photo of Kryten's birthday party. (00:03:30)
Timeslides - S3-E5
Continuity mistake: When Lister and Gilbert are looking at the statue of Lister in the courtyard, Lister has his arms crossed in an angle from above, but when the shot cuts back, his arms are at his side, before crossing them again. (00:19:25)
Timeslides - S3-E5
Continuity mistake: When Lister is looking through Hitler's briefcase, he finds a banana and crisps sandwich with a bite taken from it. When Rimmer takes a bite out of the same sandwich later in the episode, the sandwich is whole. (00:08:30 - 00:26:15)
Continuity mistake: When the Polymorph is switching between various appearances at the start, it stops at a rabbit. When the Polymorph stops at the rabbit, there is a damp stain beside the two yellow lines on the floor. This damp stain was not there when the Polymorph was switching between other forms. The stain just suddenly appears out of nowhere. (00:01:45)
Continuity mistake: After Starbug and Blue Midget leave Red Dwarf, there is a shot of Blue Midget driving away from the ship, towards the camera. Cat and Kryten are the only two on board as Rimmer and Lister are on Starbug, but there are three people shown inside Blue Midget. This is because the shot was taken from series two, in which Rimmer, Lister and Cat were inside it. (00:03:25)
Continuity mistake: When Lister is telling Rimmer that he is going to die and that Rimmer doesn't need food, there is snow over his face, hair and coat collar, but a few seconds later, the snow has mostly disappeared. (00:09:35)
Continuity mistake: Rimmer wears a hat with an antenna on the right hand side when on Starbug, and after arriving on Earth, but when he and Kryten are walking through the streets later on, the antenna is now on the left side of his hat, and is far more extended. (00:02:20 - 00:08:00)
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