Writer:	Russell T. Davies
Director:	Graeme Harper
Star:	David Tennant (The Tenth Doctor),  Freema Agyeman (Martha Jones),  John Barrowman (Captain Jack Harkness)
Guest Star:	Deborah MacLaren (Kistane),  Abigail Canton (Wiry Woman),  René Zagger (Padra),  John Bell (Creet),  Robert Forknall (Guard),  John Simm (The Master),  Derek Jacobi (The Professor),  Chipo Chung (Chantho),  Neil Reidman (Lieutenant Atillo),  Paul Marc Davies (Chieftain)

Parts of this episode were filmed using the same location (a disused paper mill in Wales) for The Impossible Planet and The Satan Pit, albeit a different area within that location. (edit) The opening scene was filmed in Cardiff Bay by the Wales Millennium Centre and Roald Dahl Plass. This has been shown before in Doctor Who in the episode Boom Town as well as extensively in Torchwood (as the Torchwood Hub is based beneath the Plass). (edit) According to the commentary for this episode, John Barrowman refused a stuntman and did the leap (where he jumps onto the TARDIS) himself. (edit) Jack says that when he went back in time to search for the Doctor he ended up in 1869. This is ironic because the Doctor (at the time played by Christopher Eccleston) and Rose visited 1869 in episode 3, series 1, "The Unquiet Dead" and they were in Cardiff, the city that Jack later made his home. That's how close Jack came to meeting them. (edit) Overnight viewing figures for this episode were 7.3 million, with a final viewing figure of 7.84 million. (edit)

The Professor: The Doctor? (points to jack)
The Doctor: That's me.
The Professor: Good, good, good, good good good good good good!
The Doctor: It's good apparently. (edit) The Doctor: The rift bleeds energy. Every now and then I need to open up the engines and soak up the energy and use it as fuel.
Martha: So it's a pit stop!
The Doctor: Exactly. It should only take 20 seconds. The rift's been active. (edit) The Professor: The call came from across the stars, over and over again. ‘Come to Utopia’. Originating from that point.
The Doctor: Where is that?
The Professor: Oh, it’s far beyond the condensed wilderness, out towards the wildlands and the dark matter reefs, calling us in. The last of the humans scattered across the night.
The Doctor: What do you think’s out there?
The Professor: We can’t know. A colony? A city? Some sort of haven? The science foundation created the Utopia project thousands of years ago to preserve mankind, to find a way of surviving beyond the collapse of reality itself. Perhaps they found it. Perhaps not, but it’s worth a look, don’t you think?
The Doctor: Oh yes. (edit) The Master: (after being mortally wounded by Chantho) Killed by an insect. A girl. How inappropriate. Still, if the Doctor can be young and strong, then so can I. The Master, reborn!
(The Master regenerates) (edit) The Master: Did you never think, all those years standing beside me, to ask about that watch? Never? Did you never once think, not ever, that you could set me free?
Chantho: Chan, I’m sorry, tho! Chan, I’m so sorry!
The Master: You… with your chan and your tho, driving me insane!
Chantho: Chan, Professor, please…
The Master: THAT IS NOT MY NAME! The Professor was an invention; so perfect a disguise that I forgot who I am.
Chantho: Chan, then who are you, tho?!?
The Master: I… am… the Master!
(The Master electrocutes Chantho) (edit)

As can be seen when Captain Jack enters the irradiated chamber, one hundred trillion years into the future, humanity is still using the QWERTY keyboard. (edit) The Professor states that he was found as a child on the Silver Devastation. In The End Of The World, this is stated as being the home of the Face of Boe. (edit) According to the commentary for this episode, the Professor's attire (white shirt, waistcoat, etc.) was supposed to be an homage to William Hartnell, the original Doctor. (edit) The watch that the Professor has is identical to the watch John Smith had in Human Nature and The Family Of Blood. (edit) Reference is made to Boom Town, when the Doctor mentions ‘trouble with the Slitheen’ and being ‘a different man’ (he was in his ninth incarnation at that point). (edit)

Captain Jack: So what about those things outside, the beastie-boys?

The Beastie Boys are a musical group from New York, who have enjoyed over 20 years of international critical acclaim and commercial success. The name 'Beastie' originally stood for "Boys Entering Anarchistic States Towards Internal Excellence". They are one of the longest-lived hip-hop acts. Their biggest hits include 'Fight For Your Right (To Party)', 'Sabotage'and 'Intergalactic'. (edit) The Doctor: It’s built on a rift in time and space, just like California and the San Andreas Fault.

The San Andreas Fault is a geological fault that runs around 800 miles through western and southern California. The fault was first identified in Northern California by UC Berkeley geology professor Andrew Lawson in 1895 and named by him after a small lake which lies in a linear valley formed by the fault just south of San Francisco, the Laguna de San Andreas. Following the 1906 San Francisco Earthquake, it was Lawson who also discovered that the San Andreas Fault stretched well southward into Southern California. (edit) The savage look of the Futurekind, combined with the time setting of the story, is an allusion to H. G. Wells's novel 'The Time Machine'. In fact, in "Doctor Who Confidential", Russell T. Davies mentions the influence of "Mad Max" in the look of the Futurekind.. (edit) The title 'Utopia' refers to the 1516 book written by Sir Thomas More (1478-1535) which describes an imaginary island that holds a perfect social, legal and political system where all evils of society have been removed. (edit)