It's called Day of the Doctor, and it's showing on the 23rd November 2013
The feature length episode title was officialy revealed as The Day of the Doctor, which frankly doesn't give much away.
David Tennant and Billie Piper
Former Doctor David Tennant will reunite with former companion and unrequited love Rose (Billie Piper) for the special. They will team up with current Doctor and companion Matt Smith and Jenna Colman. The two Docs apparently love working with each other, proving that the Tardis is big enough for the both of them.
Baddies: Daleks and the Zygons
Come on, the Daleks were never going to miss the Doctor's big day, were they? The tin-pot dictators will return, along with an enemy we've hardly glimpsed since their first appearance almost 40 years ago: the creepy shape-shifting Zygons.
Kate Stewart (Jemma Redgrave) – daughter of the legendary Brigadier Alistair Lethbridge-Stewart and head of scientific research at the United Nations Intelligence Taskforce – will be returning to fight alongside the Doctor. Fans are hoping that means a rematch between the Zygons and UNIT, who last tangled in 1975's Terror of the Zygons.
Who is John Hurt?
Well, John Hurt is Who. As revealed at the end of the last series, John Hurt plays a previously unknown version of the Doctor. According to costume designer Howard Burden, he is a 'dark' Doctor who fits in between Paul McGann (who starred in the 1990s TV movie) and Christopher Eccleston. He said: “There was a gap between Paul McGann playing the Doctor and Christopher Eccleston, when we didn’t see a regeneration, and John Hurt will fit into that gap. He is a past Doctor, not a future Doctor.”
The Time War, Bad Wolf and a Red Sonic Screwdriver
Careful inspection of the poster seems to reveal the story will involve the last great Time War between the Time Lords and the Daleks, while John Hurt's Doctor might wield a red sonic screwdriver. Also featured: a possibly exploding Tardis and the words 'Bad Wolf', a reference to the very first series of the relaunched Doctor Who.
It will be shown around the world, in 3D
To avoid spoilers, the special will be shown in over 200 countries at the same time, the biggest simulcast in history. British viewers will be able to watch the special in 3D at cinemas.
American fans have seen more than the rest of us
Guests at the San Diego Comic-Con got a sneak peak of the anniversary special's trailer, and no-one else was allowed to see it. This annoyed people, quite a lot.
Peter Davison is making an appearance during the 50th Anniversary, but we don't where, when or in what way. He implied that other former Doctors are taking part. "It is a big year for the show and we're all doing our bit for it. Trust me." However, Stephen Moffat squashed hopes of a "traditional massive reunion", saying ""We can't do eleven Doctors! Three of them are dead!"
Matt Smith is still around for the Christmas episode
And he'll be wearing a wig. Here he is on set, frollicking with a Christmas turkey and sporting a hairpiece to cover his shaved head.
It also means new Doctor-in-waiting Peter Capaldi is unlikely to make an appearance in the 50th, but then again, who really knows...?
This could all be wrong
Stephen Moffat claims he has lied until his pants burned in order to keep the true story a secret, and for once we believe him...