The Fourth Dimension
The God Complex
It's Marcus! The picture of Gold that Amy checks out in the opening minutes is actually a photograph of Doctor Who producer, Marcus Wilson.
It's Nick! This is the second episode in a row directed by Nick Hurran who made his Doctor Who directorial debut in The Girl Who Waited.
It's hell! This is the second adventure in a row where one of the female characters voices a belief that she's in hell.
It's a Rubik's Cube... again! The Doctor had a crack at one in Night Terrors and again toys with one of the puzzles, early in The God Complex.
The God Complex was originally intended to be part of the Eleventh Doctor's first series. Toby Whithouse instead contributed The Vampires of Venice for that run and The God Concept was later developed for 2011.
'Oh, look at you... you are beautiful!' The Doctor's exclamation when he sees the Minotaur echoes his comment, 'Oh, you are beautiful!' which he made whilst addressing the Clockwork Robot in The Girl in the Fireplace and earlier when he saw the werewolf in Tooth and Claw.
The Minotaur is a creature from Greek myth; part man, part bull, the being was kept in the Cretan Labyrinth.
The Doctor references the Nimon, a technologically advanced race that resembled Minotaurs. They were defeated by the Fourth Doctor in The Horns of Nimon.
Joe's verse ('Here comes a candle to light you to bed...' etc) is from the centuries-old children's rhyme Oranges and Lemons.
When the Doctor opens the door to room number 11 we ostensibly hear the Cloister Bell, part of a warning system in the TARDIS first heard in Logopolis.
The God Complex features Caitlin Blackwood as the vision of young Amy. We last saw her in Let's Kill Hitler and here she recreates her waiting posture - seated on a small suitcase - as seen in her debut story, The Eleventh Hour.
Amy first met the Doctor in The Eleventh Hour she was 7 years old. Amy's room number was 7. The Doctor's was 11 and, of course, he is the Eleventh Doctor.
The Third Doctor fought a version of the Minotaur in The Time Monster and earlier, the Second Doctor adventure, The Mind Robber, featured a form of the being along with several other mythical creatures including a unicorn!
David Walliams is a massive fan of Doctor Who and says he got Tom Baker to work on Little Britain because he was such a devotee of the Fourth Doctor!