Visible crew/equipment: When Lister and the Cat are walking through the corridor on the ship, the top of the set is visible through the transparent ceiling. (00:03:55)
Visible crew/equipment: When Lister puts his mutton vindaloo on the DNA modifier, the pole used to make the vindaloo float can be seen when the beam is cast on the dish. (00:22:55)
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