The Fourth Dimension
Army of Ghosts
The aerial shot of One Canada Square in Canary Wharf is taken from the opening credits of The Apprentice.
Get Out Of My Pub!
Although seen as part of a fictional TV show in this episode, the world of EastEnders has appeared as part of the Doctor Who universe. Characters from both shows appeared alongside each other in the 3D adventure Dimensions In Time as part of 1993's Children In Need appeal.
Actress Freema Agyeman so impressed the production team as Adeola that she was offered the chance to take over from Billie Piper as the Doctor's new companion. The rest, as they say, is history.
Fake ghosts have featured in previous adventures, including a device used to frighten people away from Magnus Greel's hidden sewer lair in The Talons Of Weng Chiang (1977).
The story was originally going to be set in Cardiff, near the Time Rift on which the Torchwood Hub is now built.
Time And Relatives
It was later revealed in Smith And Jones that doomed Adeola was the cousin of future companion Martha Jones.
Freema Agyeman is the second companion to be cast as such following a guest role in the series. Lalla Ward got the job of Romana 2 after playing Princess Astra in the Armageddon Factor (1979).