Continuity mistake: Just before Rimmer and Lister drink the hooch, Lister's locks are behind his back, then one of the locks moves to in front of his left shoulder during a brief shot of Rimmer. (00:13:30)
Continuity mistake: When Rimmer gives Hollister the directives to sign, he holds the clipboard in both hands. In the next shot his left hand is under the first page. (00:02:15)
Continuity mistake: When Hollister picks up the lemon drink, his left hand is by his side. In the next shot it is on his chest. (00:01:50)
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