• This episode is the Tenth Doctor's penultimate episode, and part one of his regeneration story.
• This episode marks the return of John Simm as the Master, who was last seen in the Series 3 finale, Last of the Time Lords.
• This is the first time in the revived series that Gallifrey has been seen (excluding flashbacks).
• The title for this episode was confirmed by the official Doctor Who website on November 19th 2009. It's the first new series two-parter to have both of its instalments filed under the same name.
• John Simm's name flying through the vortex marks the first time in the revived series that an actor playing a villain has been credited in the opening titles.
• When the Doctor is telling Ood Sigma about what he has been doing since he was summoned to the Ood Sphere in The Waters of Mars, he implies that he married Queen Elizabeth I. This could explain her reaction when she saw him at the end of The Shakespeare Code and ordered his execution. Domestics!
• The first trailer for this episode was revealed during the Doctor Who panel at the San Diego Comic-Con convention in July 2009. The teaser included the narration from Timothy Dalton, shots of Catherine Tate in role as Donna Noble, Bernard Cribbins as Wilfred Mott, and a mysterious figure wearing a black hood, later revealed to be the Master.
• This episode aired on 26th December 2009 in the US, 2nd January 2010 in Canada, 7th February 2010 in New Zealand and 14th February 2010 in Australia.

• The Narrator: It is said that in the final days of Planet Earth, everyone had bad dreams. To the west of the north of that world the human race did gather, in the celebration of a pageant right to banish the cold, and the dark. Each and every one of those people had dreamt of the terrible things to come, but they forgot. Because they must. They forgot their nightmares of fire and war and insanity...
• Elder Ood: There is a man, so scared.
  The Doctor: Wilfred! Is he alright? What about Donna, is she safe!?
  Elder Ood: You should not have delayed. For the lines of convergence are being drawn across the Earth, even now.
• Elder Ood: The Darkness heralds only one thing: the end of time itself.
• Lucy: Can't you see!? He lied to you! His name isn't even Harold Saxon!
  Governor: And this was written also. For his name is... the Master!
• Lucy: 'Til death do us part, Harry!
• Wilf: I keep seeing things, Doctor. This face, at night.
  The Doctor: Who are you?
  Wilf: I'm Wilfred Mott.
  The Doctor: No. People have waited hundreds of years to find me and then you manage it in a couple of hours.
  Wilf: Just lucky, I suppose.
  The Doctor: But we keep on meeting, Wilf. Over and over again, like something's still connecting us.
• Wilf: Sometimes I see this look on her face. Like she's so sad, but she can't remember why.
• Wilf: How about you? Who have you got now?
  The Doctor: No one. Travelling alone. I thought it was better. But I did some things, it went wrong. I need...
• Donna: Never too early for margheritas, that's what I say!
• Joshua: You can resume work on Boxing Day, Mr Saxon.
  The Master: My name... is the Master!
• Master: Oohh, you're gonna love this!
• The Narrator: And so it came to pass, on Christmas Day, that the human race did cease to exist. But even then, the Master had no concept of his greater role in events. For this was far more than humanity's end. This day was the day upon which the whole of creation would change forever. This was the day the Time Lords returned. For Gallifrey!
  Time Lords: For Gallifrey!
  The Narrator: For victory!
  Time Lords: For victory!
  The Narrator: For the end of time itself!
  Time Lords: For the end of time itself!
  

DVD
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