Other mistake: When Cat picks up the can of Leopard lager which is invisible to Lister, he shakes it, pops the cap and sprays Lister with foam. The foam is visible but the can remains invisible, and that makes no sense. If we are seeing the scene from Cat's point of view the can and foam should both be visible, and if it is from Lister's then neither should be.
Factual error: While it is true that lithium carbonate can be used to treat depression and other psychiatric disorders, it cannot be administered in gaseous form. It is a very stable salt and only starts to form vapour at 1,310 degress Celcius. Spraying it about as a 'mood stabliser' at that temperature, as Kryten does, is going to kill everyone on the spot.
More mistakes in Red Dwarf
Trivia: It was rumored that Alfred Molina and Alan Rickman wanted the part of Rimmer. Lee Cornes also auditioned for this role (he later guest starred on the show), as did Hugh Laurie. Robert Bathurst, Norman Lovett and David Baddiel auditioned for the role of Lister.
Trivia: "Meltdown" was originally planned to be the first episode of Series IV of Red Dwarf. However, the militaristic tone of this episode - and in particular Dave Lister's strident anti-war speech near The End of the episode - meant it fell foul of the BBC censors. The original planned transmission date (Feb 14 1991) coincided with the outbreak of "Operation Desert Storm" - the Gulf War...and the BBC felt that an "anti-war" episode of Red Dwarf would be inappropriate for a country at war with Iraq.
Lister: Get real, man. Most eunuchs have got more balls than you.
Quarantine - S5-E4
Kryten: What a smee... What a smee... What a smee - hee.
Question: When Holly is saying about how he has changed music he says that because of the 2 new notes he's made instruments would be bigger. "Triangles will have four sides. Piano keyboards the length of zebra crossings. Course, women will have to be banned from playing the cello." I don't understand the joke about the cello part. Could someone please tell me what he means?
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.
Chosen answer: In-universe, after leaving Red Dwarf after his first appearance, Kryten managed to crash Lister's space-bike into an asteroid. Lister found his remains and decided to rebuild him, however, due to the high level of damage and Lister's questionable repair skills, he was unable to recreate Kryten exactly, leading to changes in appearance, personality and accent. In reality, the original actor wasn't available, coupled with presumably practical concerns about one-off makeup as opposed to makeup for a regular cast member, so some visual changes were made.
Suggested correction: Lister can only see M-Corp products and M-Corp employees. Cat is not an employee of JMC or M-Corp, so he disappears. Lister is the only member of the crew who is employed by M-Corp at this point.
Suggested correction: Cat was a descendant of the cat Lister brought aboard Red Dwarf. Would it be possible that the new owners might have stricter security controls, and Lister was sent to Stasis for a different reason?
Andy Benham ★
Inventing Deux ex machina explanations for a plot hole doesn't make it any less of a plot hole. M-Corp erases all of the Jupiter Mining Corporation's equipment, personnel and infrastructure from Lister's life. In no way is Cat a part of that. He has no connection at all to the Jupiter Mining Corporation, and until he meets him in Episode 1 no connection to Lister, either.
If M-Corp only erased JMC equipment from Lister's life, then Kryten, who belongs to DivaDroid and not the JMC, wouldn't have disappeared either. He disappears as he doesn't belong to M-Corp, not because he belongs to the JMC. Cat has no connection to M-Corp, as he wasn't a part of the JMC (as you pointed out), and is therefore erased for Lister.