Visible crew/equipment: When Lister, the Cat and Kochanski arrive in the game and start walking towards the camera, a boom mic bobs briefly into the shot. (00:03:55)
Terrorform - S5-E3
Visible crew/equipment: A boom mic shadow can be seen along the bottom of the screen when the crew have to leave Starbug and walk. (00:11:25)
Terrorform - S5-E3
Visible crew/equipment: When Lister, Cat and Kryten leave the cockpit with the plan to make Rimmer feel good about himself to escape, a boom mic can be seen in the top left corner of the screen. (00:22:45)
Visible crew/equipment: At the start of the episode, when Lister and Kryten talk about Lister's comic, a boom mic shadow can be seen on Kryten's head. (00:02:10)
Confidence and Paranoia - S1-E5
Visible crew/equipment: When the skutters try to move Lister in the Medi-bay, you can see the cable which pulls Lister's chair in the bottom right of the screen. (00:12:40)
Visible crew/equipment: Just before Red Dwarf explodes, there is a shot of Lister. In the background you can see a moving shadow of a crew member on the floor. (00:04:25)
Visible crew/equipment: At the start of the episode when the Nazi attacks Ace in the plane, a boom mic can be seen at the top of the screen. (00:00:55)
Out Of Time - S6-E6
Visible crew/equipment: In the medi bay when Kryten says, 'I'll have a talk with him droid to droid,' a boom mic is visible at the top of the screen. (00:05:55)
Emohawk - Polymorph II - S6-E4
Visible crew/equipment: Just after the grenade explodes, a boom mic shadow can be seen on Kryten's head. (00:27:00)
Gunmen of the Apocalypse - S6-E3
Visible crew/equipment: When the simulant has beamed on board Starbug, Lister and The Cat get up slowly from the table. Look closely, and you can see the shadow of a boom mic cast on Lister and The Cat. (00:07:50)
Visible crew/equipment: When the alligator lands on the German guards, a fluffy grey boom mic can be seen at the top of the screen. (00:04:25)
Visible crew/equipment: If you look closely when the camera follows Lister (in the scene just before the meteor crashes onto Starbug) you can actually see the edge of the set and some studio lights. (00:04:10)
Visible crew/equipment: In the cell at the start of the episode, after Rimmer says they have to escape, a boom mic is visible at the top of the screen. (00:03:10)
Rimmerworld - S6-E5
Visible crew/equipment: When Rimmer argues that they should not board the simulant ship, the shot of Lister in the foreground and Rimmer in the background shows a boom mic just above Rimmer's head. (00:04:40)
Visible crew/equipment: After Rimmer injects himself and speaks to Captain Hollister, a boom mic can be seen at the top of the screen. (00:26:25)
Visible crew/equipment: When Rimmer is getting in the car on the beach, you can see the cameraman's reflection on the side of it. (00:18:25)
Visible crew/equipment: When the Cat licks Better Than Life's host, there is a shadow of a boom mic at the top of the screen on the wall. (00:19:35)
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