There is nothing small about the finale to Season 6 of Doctor Who. It has dinosaurs and Romans and the Silence, completes the story arc in which River Song shoots the Doctor by the shores of Lake Silencio, reunites the Doctor with Winston Churchill, encourages him to grow a beard, and even has a decent stab at killing Rory Williams again.

All this, and it's not even a two-parter. Here are a few things to keep an eye out for, the next time you watch:

(The episode is available on iTunes and Amazon.)

The moment where the Doctor calls his old friend the Brigadier is inspired by the death of actor Nicholas Courtney. Steven Moffat said that he was writing this episode when the news arrived, and included that call as a tribute to one of the Doctor's oldest friends: "In a story about the Doctor going to his death, it seemed right and proper to acknowledge one of the greatest losses Doctor Who has endured."

Also, the eyedrives worn to ward off the Silence were inspired by an eyepatch Nicholas Courtney worse when playing an alternate reality version of the Brigadier in the Third Doctor story "Inferno".

https://www.youtube.com/watch?v=XyEuIcF5yQ4

The sequence in which the Doctor plays Live Chess with Gantok is notable for two reasons. One is that Gantok is played by Mark Gatiss, but credited to one Rondo Haxton - a secret name inspired by the American horror actor Rondo Hatton. Hatton had acromegaly, which gave his features a particularly distorted look, perfect for playing baddies in 1940s movies such as The Brute Man and The Pearl of Death.

The other is that Steven Moffat invented the idea of a deadly electrified version of chess because, in his opinion, chess is "one of the most boring games in the world."

Moffat also threw in the "hello Dalek" scene as a playful way to thwart the British press, to whom he had been insisting that the Doctor's most famous enemies would be taking a break during Season 6.

Meredith Vieira filmed her contribution as part of a location report from the set, in Cardiff's Upper Boat Studios. Her eventual report, which came out before the episode aired, did reveal that Ian McNeice would be returning as Winston Churchill and that Richard Hope would appear as the Silurian Malohkeh. But it also included several Cybermen, which were included to throw fans off the scent.

https://www.youtube.com/watch?v=89bRg50io9M

The British side of the news media was represented by two presenters who will have been as well known to British viewers as Meredith is to American Whovians, namely Bill Turnbull and Sian Williams of BBC Breakfast News:

https://www.youtube.com/watch?v=yihI9xP8kcQ

The Doctor is seen reading a magazine called Knitting for Girls. Sadly no such magazine exists in real life.

As the Doctor enters the Seventh Transept, he says "I hate rats," a nod to similarly imposing underground burial chamber of skulls in Indiana Jones and the Last Crusade.

The first time Doctor Who mentioned the idea of a point in history which cannot be altered, even by the Doctor, was as far back as the First Doctor adventure "The Aztecs", in which the Doctor even uses the phrase "you can't rewrite history, not one line" that River Song later references at the end of "Forest of the Dead":

https://www.youtube.com/watch?v=sPON2CJVU84

...although the term "fixed point" didn't come into common use until the modern era of the show:

https://www.youtube.com/watch?v=-77eKQ2IP5A

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