Character mistake: Rimmer asks Kryten to make the new computer blonde. When the computer launches, the computer's hair is brunette. (00:07:30 - 00:08:45)
Suggested correction: It's possible that, rather than making a mistake, Kryten simply ignored the request.
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.
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.
Answer: In the book, the Cat finds the concept of a name confusing, as he's convinced he's the center of the universe and the idea that someone wouldn't know who he was is baffling.