For those fans of Doctor Who, who may not be aware of quite how much rich heritage the show has, here is a rundown of all the references to previous stories I could find in the 50th anniversary special.
1. The original titles used instead of the modern titles.
2. A policeman as the first shot, echoing the first shot of the very first episode in 1963.
3. Sign for 76 Totters Lane, the junkyard where the TARDIS was stored in the first episode.
4. Coal Hill School - the school Doctor Who's granddaughter Susan attends in then first episode.
5. Chairman of Governors at Coal Hill School - I. Chesterton. The original Doctor's first male travelling companion.
6. Headmaster W. Coburn, Anthony Coburn wrote the first Doctor Who serial.
7. Clara is a teacher at Coal Hill school, same as Ian and Barbara in the first episode (Ian and Barbara being two of the three travelling companions of the first Doctor)
8. Clara leaves the school grounds at 5.16pm, the time of the first epiosde's transmission.
9. The UNIT callsign of Greyhound is used again by the helicopter picking up the TARDIS.
10. Osgood is wearing the Fourth Doctor's scarf.
11. Kate Lethbridge-Stewart appeared in the episode 'The Power of Three' and is the daughter of Brigadier Lethbridge-Stewart
12. Kate mentions Malcolm, the UNIT scientist played by Lee Evans in 'Planet of the Dead'
13. The Doctor mentions the Brigadier, but not by name.
14. Queen Elizabeth the 1st is mentioned, she met the 10th Doctor in 'The Shakespeare Code' and he was mentioned to have married her previosl to arriving on the Ood planet in 'The End of Time - Part 1'
15. Fall of Arcadia is mentioned and then shown.
16. We see the last day of the Time War which is mentioned throughout the return of Doctor Who from 2005.
17. The Time-Lord uniforms once again bear the seal of Rassilon.
18. According to members of Gallifrey's War Room, the High Council's plans when in emergency session failed. We saw these plans in 'The End of Time - Part 2'. Hopefully Rassilon was deposed after the unsuccessful attempt to pull Gallifrey from the Time-Locked Time War!
19. The Omega arsenal is mentioned, perhaps a reference to Omega, the stellar engineer who gave Gallifrey the power source necessary for Time Travel.
20. The 'moment' is mentioned, it was previously mentioned by the High Council of Time-Lords in 'The End of Time - Part 2'
21. The conscience of 'The Moment' resembles Rose Tyler, companion of the 9th and 10th Doctors.
22. The conscience of 'The Moment' mentions Bad Wolf, the running theme of the first season of the 2005 continuation.
23. The 10th Doctor played by David Tennant appears in a painting in the gallery.
24. The Doctor rides a white horse, similar to the one seen in 'The Girl in the Fireplace'
25. We see a Zygon for the first time since 'Terror of the Zygons' in 1975.
26. The 10th Doctor partially recreates the speech from 'Voyage of the Damned'
27. The Fez once more makes a reappearance!
28. Kate Lethbridge-Stewart mentions the 'Cromer' incident file. Of course referring to the television story 'The Three Doctors'
29. The Doctors attempt to 'reverse the polarity' something the third Doctor often did.
30. The phrase 'Timey-Wimey' is used again, a common 'Moffatism'
31. The Tower of London is first used as UNIT's headquartes in the 2005 Christmas special.
32. The Black Archive has countless pictures of previous companions.
33. The Vortex manipulator of Captain Jack Harkness is shown.
34. The 11th Doctor mentions that Clara has 'met' the 10th Doctor and the War Doctor before. This was at Trenzalore in the Doctor's tomb.
35. The roundels make an appearance in the TARDIS
36. The Doctor's comment about 'You've redecorated, I don't like it' echoes the comment make by the second Doctor in 'The Three Doctors' and 'The Five Doctors'
37. The Doctor uses the Space/Time telegraph, used by the Brigadier to bring the Doctor back to Earth in, suitably enough 'The Terror of the Zygons'.
38. We see a cyberman head (Cybus industries version)
39. The moment mention the TARDIS's 'wheezing groaning' sound. Terrance Dicks, former script editor and writer of several Doctor Who stories, was the most prolific writer of Doctor Who novels, and he always described the TARDIS noise in that exact way in his books.
40. We see all the Doctors including the 13th Doctor, Peter Capaldi. Footage is taken from old stories for Doctors 1-9.
41. Geronimo!
42. Allon-sy!
43. In John Hurt's regeneration he says 'wearing a bit thin' echoing what Hatnell says before regeneratin in the 1966 story 'The Tenth Planet'
44. He also says 'I hope the ears are a little less conspicuous this time' a reference to Ecclestone's prominent ears.
45. The 10th Doctor says that it is reasurring thatn his future is in safe hands, this is what the 1st Doctor says to the 5th at the end of 'the Five Doctors'.
46. The 10th Doctor saying 'I don't want to go'
47. In the dream sequence we see the 12 Doctors.
48. Tom Baker makes an appearance as 'The Curator' a possible future incarnation of the Doctor? It is implied that one day the Doctor will retire after regenerating into an older version of one of his old bodies.
49. The credits feature images of all 12 Doctors.
Think that's them all. If I missed any, please let me know.