Revealing mistake: When Pree shows Lister his Medi-Bay file, it is a flipped shot. Note the danger sign next to the computer. (00:27:40)
Continuity mistake: When Lister notices the video, the silhouette of a flashing blue light is cast on the table (to the left of screen). In the next shot, there is no sign of the flashing blue light. (00:10:40)
Deliberate mistake: When the computer has been launched, Lister walks into the drive room and notices the computer and stands behind Kryten and Rimmer. But when the camera is focused on the computer, there is no sign of Lister what so ever. (00:10:00)
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)
Other mistake: An option for the new computer is breast size. A meaningless addition, since the computer is just a head. (00:07:35)
Suggested correction: When setting up the computer, there is an option for frame size. Kryten chooses close up, and when Pree appears on-screen Rimmer reacts to the fact that her breasts aren't visible whilst Kryten says that he likes that frame size. Presumably, there were other frame sizes available that would reveal more of Pree's body, giving meaning to the option.