 Although supposed to be a bottle episode with simple 'dialogue' for the series, Grant and Naylor found it hard going.The main scene of the Cat, Lister and Kryten arguing in the quarantine bay took a grand total of 57 minutes to record, the cast either breaking up with laughter or else having trouble with dialogue that had only recently been delivered.The increasing frustration did, however, add to the effectiveness of the scene

The original idea was to have each of the crew infected with Psi-powers, but this was later changed to the positive viruses story.