Revealing mistake: Near the end of the episode, Kryten and his employer are seen arguing in supposedly backwards English. However, when you watch the episode how the people of earth would see it on the second DVD, Kryten and his employer aren't speaking English, they are just speaking plain gobbeldy-gook, even although when you see the people of Earth talking on the DVD they speak correctly.
Revealing mistake: When Rimmer stands up from underneath the table, just before he says, "Thanks for your support" to Lister, listen very carefully and you can hear the stunt director saying "Action!" backwards. This shot was the splice point between the reversed and the regular footage. (I know this mistake is listed as being in the 'backwards version' on the DVD, but it is in the regular broadcast version too - you just have to listen harder for it.)