1. The original title sequence from 1963 kicked off the episode.
2. Totter’s Lane, where the First Doctor parked his TARDIS while his granddaughter Susan Foreman was at school, got a lovely wink at the opening of the episode.
3. And here’s Coal Hill School itself, where companions Ian Chesterton and Barbara Wright taught. Look closely…
Chairman of the Governors: Ian Chesterton!
And right under that it reads “W. Coburn”, which is probably a nod to Anthony Coburn, who helped developed Doctor Who back in the ’50s and is believed to be behind the idea that the outside of the TARDIS should look like a police box.
6. Speaking of TARDIS redecoration…
7. A machine that goes “ding” was back.
8. These Queen Elizabeth gags were finally explained! Doctor, you naughty boy.
No wonder she wanted your head in The Shakespeare Code.
10. Ten’s last words broke our hearts a little bit all over again.
16. Kate’s not the only Lethbridge(-Stewart) who’s had to deal with multiple Doctors.
17. River’s shoes are apparently a weapon of mass destruction worth keeping in the Black Vaults.
Not that this is actually surprising, come to think of it. Via.