http://www.trekbbs.com/showthread.php?t=225298&page=3 It's extremely unlikely that it's related to the Christmas episode. To not have classis Doctors in the 50th episode but then have one show up at Christmas?? Not gonna happen.
Remember that the final scene of "The Name of the Doctor" was filmed four months after the rest of the episode with the anniversary special filming. It's not out of the realm of possibility that Moffat and his team could schedule pick-up filming for the anniversary special during the Christmas special's block. It would be a continuity nightmare (film continuity, not narrative continuity), but not impossible.
This isn't from the Christmas special, or even from Doctor Who for that matter. They were shooting a trailer for the new series of "Have I Got News For You". Link
It's Moffat so take with the usual bag of salt but some potential spoilers for the episode here: http://www.doctorwhotv.co.uk/did-moffat-drop-some-hints-on-smiths-final-episode-53244.htm So Yay for him remembering that "silence will fall" originally refered to silence actually falling but Boo for us never finding out who blew up the TARDIS. (And no it wasn't The Silence. If they had that sort of power they could have killed the Doctor any time they wanted without needing any ridiculously complicated schemes.)
I thought it was fairly obvious that it was the Order of the Silence, attempting to hijack the TARDIS in order to prevent the Doctor from traveling to the Fields of Trenzalore and answering the question, "Doctor who?".
They can casually destroy one of the most powerful objects in the Universe but can't build a spacesuit without help? And if they can do it once, why not keep doing it until they get it right?
1. What makes you think the destruction of the TARDIS was deliberate? I took that to have been the accidental side-effect of their remote hijacking attempt. 2. Who says that the Order of the Silence's attempts to create the spaceship vs. hijack the TARDIS took place anywhere near one-another in their own chronology? One could have happened centuries after the other for them.
Yeah, I'm not quite buying that it was the Silence either. Theres still that mysterious voice in the Tardis to explain. Hopefully its just Moffat giving us a wink with his obviously feeble attempt to distract us from the question.