At 13:24 into the episode, the controller says that he wrote for "The Ensign" magazine for the character Captain Jack Harkaway - 5,000 words a week for 25 years. Zoe (who is supposed to be super-smart) says, "That's over half a million words!". Actually, the total comes out to over six million words (6,500,000).
This episode was watched by 7.3 million viewers on its original transmission.