Revealing mistake: When Ghandi explodes, there is a single shot where he had disappeared before the explosion goes off. (00:22:35)
Revealing mistake: When Lister and Rimmer first meet their femaile opposites, Lister takes a step back and brushes against Rimmer's hologramatic shirt. (00:10:30)
Stasis Leak - S2-E4
Revealing mistake: When Rimmer hides under the table, he is not visible beneath the table when Lister and Rimmer walk in. (00:18:40)
Continuity mistake: When Lister and Rimmer talk to Holly at the disco, Lister's arm is on the table. When the camera angle changes, it is on his lap below the table. (00:21:15)
The Last Day - S3-E6
Plot hole: In this episode Kryten has no idea how to operate a bazookoid, yet earlier on in 'Polymorph' he was able to change the settings of one from standard to heat-seek and fire it without a problem. (00:24:45)
Visible crew/equipment: When the bazookoid blasts hit the Polymorph near The End, you can see the stand that's holding the Polymorph at the bottom of the screen. (00:24:45)
Other mistake: When Lister reads Rimmer's diary, he reads the first entry, then his aunt's birthday in July and then the entry for Gazpacho Soup Day in November. Each time he looks for the next entry he flicks though the pages, yet every time he reads, it is from the start of the diary. (00:15:25)
Continuity mistake: After the future Kryten cuts off The Inquisitor's hand with the chainsaw, he kicks the glove which lands about 7 feet away from Lister. In the next shot Lister simply bends down and picks the glove up from in front of him. (00:13:45)
Continuity mistake: In 'Thanks For The Memory', both Lister and The Cat injure their left feet when they drop the gravestone; but The Cat is seen to be wearing a plaster cast on his RIGHT foot. (00:12:10 - 00:27:00)
Continuity mistake: When the gunman ties the cable to himself, he walks past a window, then in the next shot he is stood in the centre of the same window. (00:15:40)
Quarantine - S5-E4
Audio problem: When Dr. Lanstrom says 'Life without pain has no meaning' Kryten begins to speak but no words are heard before the shot changes. (00:07:10)
Revealing mistake: After Starbug lands on the 'high' Red Dwarf, Rimmer is running out of power and starts to fade in and out. However, Cat, who must be standing too close to Rimmer also fades, the backdrop being partially visible through him. (00:08:05)
Other mistake: The tax letter and Rimmer's mother's letter are both already opened before Lister takes the letters out. As there is no one else aboard Red Dwarf, the letters would not have been checked by anyone so they should still be sealed. Also, not all of the letters are already open, just the two that Rimmer receives.
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)
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