Visible crew/equipment: When Lister does the log at The Beginning of the episode, a boom mic shadow can be seen on his face throughout the scene. (00:00:40)
Visible crew/equipment: When Rimmer says that Kennedy was a fine man, a boom mic can be seen at the top of the screen. (00:20:22 - 00:21:17)
Visible crew/equipment: When Lister sneaks in to switch Kryten's head, as the camera follows Lister and goes around past the wall, the shadow of the camera can be seen in the green light. (00:09:20)
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