Audio problem: During the conversation in which Holly wants to prove he has an IQ of 6000 (while Lister and the Cat are scrubbing the floor), there is a brief moment where you can see the TV Holly is on (at an angle). You can hear sound coming from him, but his lips aren't moving. (00:16:55)
Continuity mistake: In the hologram simulation suite, the amount of smoke changes from cut to cut throughout the scene. (00:06:30)
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