Gunmen of the Apocalypse - S6-E3
Continuity mistake: When Jimmy does his trick with the whip, it knocks Kryten's hat to the floor. In the next shot it is lying on the bar. (00:20:00)
Gunmen of the Apocalypse - S6-E3
Continuity mistake: When Lister says the escape pod is not an option, his hands are apart in front of him. In the next shot, they are together. (00:12:20)
Gunmen of the Apocalypse - S6-E3
Visible crew/equipment: After Rimmer is sick, as Lister comes to his rescue, a boom mic shadow can be seen on the wall behind them near the horns. (00:18:50)
Gunmen of the Apocalypse - S6-E3
Visible crew/equipment: When sheriff Kryten asks for a drink, a boom mic can be seen at the top of the screen. (00:13:55)
Gunmen of the Apocalypse - S6-E3
Continuity mistake: Just after the virus infects the ship, the Cat is looking straight forwards. In the next shot he is looking to the far left at Lister. (00:10:45)
Gunmen of the Apocalypse - S6-E3
Visible crew/equipment: At the start of the episode when Rimmer says they should surrender, a boom mic is visible at the top of the screen. (00:06:10)
Gunmen of the Apocalypse - S6-E3
Revealing mistake: When the Cat says 'not if you believe those lying cartoons' you can see Lister mouth the line. (00:09:50)
Gunmen of the Apocalypse - S6-E3
Continuity mistake: When Lister enters the bar, he goes through the swing doors and they close behind him. In the interior shot Both Lister and the Cat have gone though the swing doors. (00:17:10)
Gunmen of the Apocalypse - S6-E3
Visible crew/equipment: When the crew's special skills get erased, a boom mic shadow can be seen on Lister. (00:24:20)
Emohawk - Polymorph II - S6-E4
Continuity mistake: Just before the damage report machine explodes, the room is full of smoke. As it explodes, all the smoke is gone. (00:07:40)
Continuity mistake: When Lister is watching the video message of a psiren, posing as Kochanski, Lister asks "How? I don't understand" and Kochanski, on the video appears to move her face beginning to reply, but when the shot cuts back to the video, Kochanski's face is suddenly still. (00:16:20)
Revealing mistake: When Legion places the hard light in Rimmer's light bee, it is noticeable that the hard light does not go inside the device. It is placed more to the area beside it. (00:09:55)
Continuity mistake: When Lister finishes pouring a glass of Bucks Fizz, he begins to place the jug back on the table with his hand still on it, but in the next shot, the jug is now on the table with Lister's hand nowhere near it. (00:20:20)
Continuity mistake: When Rimmer suggests bringing Legion with him, Lister says he's not going to come with them, and asks if he would ever join in on their late night sessions of pin the pointy stick on the weather girl. At The End of the line, Lister is looking to the right, but in the next shot, he is suddenly looking downwards. (00:12:35)
Revealing mistake: When Lister hits Legion over the head, his mask falls off. In the shot that shows Rimmer, Cat and Kryten in the foreground sitting at the table and Lister and Legion in the background, Legion's face can be seen and it is apparent that it is not the combination of the four that is his face, but in fact the actor's real face. (00:21:15)
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)
Gunmen of the Apocalypse - S6-E3
Continuity mistake: The Cat brings down the town sign by shooting the right hand side of it. Seconds later, when they pick Kryten up, the sign is hanging in front of the Livery building, which would only have been possible if he'd shot the left hand side.
Gunmen of the Apocalypse - S6-E3
Revealing mistake: At the start of the episode, we see Lister in black and white talking to Loretta. Then we cut back to what's really happening, he is playing on the AR console. Look at the door behind him, you can see Kryten's hand sticking out in the doorway. He is supposed to rush in and start talking, but you can see him waiting off camera to be told when to enter the room.
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