It took 57 minutes to film the three-minute scene with Cat, Lister and Kryten arguing in the quarantine bay. The cast kept getting their lines wrong and breaking up with laughter. This worried the producers as they only had the studio booked for two and a half hours.
The Mr Flibble hand puppet was originally made as a temporary prop for rehearsals only. Several dozen other hand puppets were bought from charity shops but none were deemed to be amusing enough. In the end, the temporary prop was used for filming.
It is said that Chris Barrie only agreed to wear the gingham dress if the other cast members would wear one too, as they appear at the end in the dresses to entertain Rimmer while he is in quarantine.
The original idea was to have each of the crew infected with Psi-powers, but this was later changed to the positive viruses story.
This is the first and only episode to contain Mr. Flibble, the insane hologramatic penguin glove puppet. However, the puppet appeared extensively in the Red Dwarf Smegazine and became a Red Dwarf icon. Mr Flibble now is the official interviewer on the official Red Dwarf website, along with Talkie Toaster. He has also become a toy glove puppet sold in numerous places. This episode also contains the first and only mention of The King of the Potato People, who would also go on to be in the Red Dwarf Smegazine.