The Doctor tells Strax to take Clara back to where they found her; as Strax had touched the Memory Worm and lost the last hour of his memory, he wouldn't remember where they found her.
This is not the first time the Doctor has been depicted wearing the trademark style of Sherlock Holmes, the Fourth Doctor previous wore the outfit in "The Talons of Weng-Chiang."
Trivia: This episode is the prequel/origin of an enemy from the Second Doctor's era, The Great Intelligence. The disembodied entity appeared in two episodes in the 60s, "The Abominable Snowmen" and "The Web of Fear." However, its origins were never explained in canon until now.
Vastra: Was she nice?
The Doctor: I just spoke to her.
Vastra: And made your usual impact, no doubt.
The Doctor: No, no impact at all. Those days are over.
Vastra: You can't help yourself. It's the same story every time and it always begins with the same two words.
The Doctor: She'll never be able to find me again. She doesn't even have the name. "Doctor." What two words?
Clara: Doctor? Doctor who?
The Doctor: When you find something brand-new in the world, something you've never seen before, what's the next thing you look for?
Strax: A grenade!
The Doctor: I suggest a full-frontal assault with automated laser-monkeys, scuttle mines, and acid.
Strax: I suggest a full-frontal assault with automated laser-monkeys, scuttle mines, and acid.
The Doctor: Why?
Strax: Couldn't we at least investigate?
The Doctor: I've had a thousand years of saving the universe, Strax. You know the one thing I've learned? The universe doesn't care.
The Doctor: Sontaran. Clone warrior race, factory produced, whole legions at a time. Two genders is a bit further than he can count.
Strax: Sir, do not discuss my reproductive cycle in front of enemy girls. It's embarrassing.
The Doctor: Typical middle child of six million.
The Doctor: Clara who?
Clara: Doctor who?
The Doctor: Oh, dangerous question.
Clara: What's wrong with dangerous?
Great Intelligence: Tomorrow the snow will fall and so will mankind.
Strax: Do not attempt to escape or you will be obliterated. May I take your coat?
The Doctor: Nice office. Big globey thing. Now, don't tell me. I see from your collar, sir, you have an apple tree and a wife with a limp. Am I right?
The Doctor: Do you have a wife?
The Doctor: Bit of a tree? Bit of a wife? Some apples? Come on, work with me here.
The Doctor: Talking snow. I love new things.
Great Intelligence: You are not of this world.
The Doctor: It takes one to snow one.
The Doctor: What are you doing here?
Strax: Madame Vastra wondered if you were needing any grenades.
The Doctor: Grenades?
Strax: She might have said "help."
The Doctor: Don't be clever, Strax. It doesn't suit you.
Strax: Sorry, sir.
The Doctor: I'm the clever one. You're the potato one.
Strax: Yes, sir.
The Doctor: Now go away.
Strax: Yes... Mr. Holmes.
The Doctor: Oy. Shut up! You're not clever or funny. And you got tiny little legs.
Strax: It's the human male from the Institute. What's he doing here? Suggest we melt his brain using projectile acid weapons and then interrogate him. (Vastra and Jenny stare) Other way around.
Francesca: Is it one of your stories? Your definitely true ones?
Clara: Ha. All my stories are true.
Digby: Like how you were born behind the face of Big Ben?
Clara: Accounting for my acute sense of time.
Francesca: And you invented fish.
Clara: Because I dislike swimming alone.
Strax: Sir, please do not noogie me during combat prep.
The Doctor: Oy, I told you to stay in here.
Clara: Oh. I didn't listen.
The Doctor: You do that a lot.
Clara: So you like me.
The Doctor: Who said I like you? (Clara kisses him)
Clara: I think you just did.
The Doctor: You kissed me.
Clara: You blushed.
The Doctor: I... when... shut up!
Clara: After you.
The Doctor: After you.
Clara: After you. I'm wearing a dress. Eyes front, soldier.
The Doctor: My eyes are always front. (starts climbing)
Clara: Mine aren't.
The Doctor: Stop it.
Clara: Look at this.
The Doctor: Go on, say it. Most people do.
Clara: It's smaller on the outside.
The Doctor: Okay. That is a first.
With this special, a new opening sequence featuring flames and swirling energy streams highlighting the 11th Doctor's face for the first time, is used along with a rescored variant of the series theme.
This special marks the debut of a new interior for the TARDIS. The new console room is far smaller than the 11th Doctor's previous one and features a console which is more high-tech, similar in appearance to the consoles of the original series.
The logo reflects the theme of the special: this one consists of a snow-filled pattern.
The special is loosely based on an outline by Douglas Adams that he wrote during his time as Script Editor on the series in 1979, describing the Doctor retiring from his role as savior of the universe.
Injoke: Clara's birthday, November 23, is the same day of the month as the "birthday" of Doctor Who: the premiere of the first episode, "An Unearthly Child," on November 23, 1963. Also, she died in December at the age of 26; the original series ended in December 1989 with "Survival", after 26 seasons on the air.
US: December 25, 2012 on BBCAmerica
Australia: December 26, 2012 on ABC1
The Doctor: You're the clever one, you're Moriarty.
Referencing the fictional nemesis of Sherlock Holmes, first appearing in order of publication in Sir Arthur Conan Doyle's "The Adventure of the Final Problem" (Strand Magazine, 1893). Although Holmes describes Moriarty as the "Napoleon of Crime" and spent months battling him, Moriarty only appears in one other Holmes story, The Valley of Fear, and is mentioned in passing in several others. Despite that, he is widely used in hundreds of derivative fictions and adaptations.