Continuity mistake: When the Nazi commander throws the crocodile at Ace, it changes size between shots. As he throws it, it is small and easy to throw, yet in the next shot it reveals it is taller than Ace. (00:01:00)
Continuity mistake: When the tent disappears, Lister's locks are over his right shoulder. In the next shot they are over both shoulders. (00:10:00)
Continuity mistake: During Ace Rimmer's funeral, the blow up doll is not visible earlier in the scene next to the Cat, but then appears from nowhere. (00:24:50 - 00:25:40)
Continuity mistake: When Lister claims his 'prize' the king's hands are on his lap. In the next shot his right hand is clutching the helmet. (00:09:05)
Revealing mistake: At The End of the episode when Ace takes off in the ejector seat, a black cable can be seen lifting the chair up. (00:27:55)
Visible crew/equipment: At the start of the episode when the Nazi attacks Ace in the plane, a boom mic can be seen at the top of the screen. (00:00:55)
Visible crew/equipment: When the alligator lands on the German guards, a fluffy grey boom mic can be seen at the top of the screen. (00:04:25)
Continuity mistake: When Ace is firing at the Nazi guards from his parachute, a white sleeve is visible. In all other shots his sleeves are brown. (00:03:00)
Continuity mistake: When Ace crashes into the boxes, Kryten's left elbow is in front of the Cat. In the next shot it is by his side. (00:28:00)
Continuity mistake: When Ace drives the bike out of the shed, the piece of wood is between the front wheel and the handlebars. In the next shot, the piece of wood is resting on his arms. (00:03:25)
Continuity mistake: At the start of the episode when the Nazi commander is speaking to Ace, in all wide shots his left arm is wrapped around the crocodile, but in all close up shots his arm is by his side. (00:00:45)
Plot hole: The alligator that falls out of the plane with Ace hits the ground several minutes after Ace does. (00:04:25)
Visible crew/equipment: When the crocodile is thrown at Ace, the crash mat is visible as he lands. The mat disappears in later shots. (00:01:00)
Revealing mistake: When Ace accelerates away from the Nazi troops, he is holding a gun in his right hand. He should not have been able to accelerate away as the throttle handle is on the right. (00:03:45)
Continuity mistake: When the Nazi commander throws the crocodile at Ace, the yellow curtain is behind ace as he falls. In the next shot, the yellow curtain is in front of him. It is clear he did not fall through the curtain as it does not move as he hits the floor. (00:01:00)
Continuity mistake: When the crew are in the cockpit when Ace Rimmer is entering their dimension, Rimmer hopes that it is not him. When he says this, there is smoke around him, but this smoke was not there in the previous shot. (00:10:45)
Continuity mistake: At the start of the scene where the crew are giving Rimmer a funeral, Lister is shown clutching his "tie", and turns to Kryten, but in the next shot, he is suddenly looking up at the ceiling. (00:24:25)
Continuity mistake: When Ace Rimmer releases the crocodile, it bites Captain Voorhese's head, and the two begin to fall when Ace removes Voorhese's parachute. When the crocodile lands on the ground a few minutes later, there is no sign of Voorhese. (00:02:15 - 00:04:25)
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