Continuity mistake: Half way through the episode, the captain's office becomes covered by a wall. (00:24:55)
Continuity mistake: When the Cat is eating the food set out by Lister, there is a cloth on the table. When Lister is asking where the other kitties are, the cloth is shown near the centre of the table. Rimmer then says he wants it off the ship, and the cloth is suddenly further to the right of the table. (00:27:45)
Continuity mistake: When Lister goes into stasis, Todd Hunter turns the wheel on the door to lock Lister in. In the next scene when Lister awakes from stasis, he just pushes the door open without turning the wheel to unlock it. Even if we are to assume that Holly would automatically open the door, the wheel should still turn to unlock the mechanism.
Continuity mistake: When Lister rides his bike in the first scene, there is a Union Jack just behind his seat. When he stops, a US flag has appeared below it. (00:01:45)
Continuity mistake: When Lister is fixing his robot goldfish, he picks it up with his right hand, then after the camera cuts, he puts it back into the tank with his left hand. (00:06:00)
Continuity mistake: The cuts on Lister's robot goldfish disappear when he throws it back into the tank after fixing it. (00:06:00)
Continuity mistake: Both Rimmer and Lister go through a door on the right hand side of the captain's office which wasn't there in the previous episode. (00:10:20)
Continuity mistake: When Lister cuts himself shaving he moves his locks behind his back, then in the next shot, they are over his shoulder again. (00:12:55)
Continuity mistake: Just before Lister cuts himself shaving, he is shaving away from himself. The camera changes and he is shaving in the oposite direction. (00:13:00)
Continuity mistake: The sign above the stasis booth in this episode is different than what it was in the previous episode, "The End". (00:14:00)
Continuity mistake: When Lister sees the future echo in the drive room, Rimmer points when he says 'Shut up.' However when the scene plays out again, Rimmer's arms stay down by his sides. (00:15:00 - 00:16:00)
Continuity mistake: When the Cat's future echo says, "I think I lost my tooth," he is at The End of the corridoor. When the present Cat say it, he is just leaving the sleeping quarters. (00:16:30 - 00:22:25)
Continuity mistake: At The End of the episode, when the future Lister and the babies appear, Rimmer has his arms folded. In the next shot, Rimmer's hands are on his hips. Also, Lister's locks change positions. (00:27:50)
Continuity mistake: When Lister is changing near the start of the episode, there are no stickers on his locker. When he leaves the room, they appear. (00:03:55 - 00:05:10)
Continuity mistake: When Lister and Rimmer are talking in their bunks, Lister says 'I've always been crazy about her'. He is looking to his right with his arm in the air, yet in the next shot he is looking down at the floor. (00:12:50)
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