The Time of the Doctor contradicted Who continuity from only two episodes prior. So what gives?
Remember that time the Doctor went to Trenzalore and there was this giant version of his TARDIS there? And then remember how the giant TARDIS had a tomb inside it where the Doctor himself is supposed to be buried? And then remember how there was a scar in time that represented the Doctor post mortem? And then remember ... oh, you get it.
The point is this -- not two episodes later, the Doctor goes to Trenzalore's past, takes part in a giant war, and ... DOESN'T DIE. It seemed to us that Trenzalore was one of those fixed-point-in-time whatchamahoodles. So where was the explanation for why it could be changed after all?
Steven Moffat was asked this very question in the latest issue of Doctor Who Magazine, and his response was very interesting.
I’ve often wondered about that. Fortunately, late one night, the Doctor turned up in person and explained it to me.
All right -- let's pretend for a moment that the Doctor popped in from the parallel universe where he's real in order to explain Steven Moffat's plot holes. It seems plausible, right? Could happen! Well, according to Moff, here's what the Doctor had to say:
Changing time is tricky. It’s a bit like a detective story: so as long there isn’t an actual body, you’ve got a certain amount of wiggle room – for instance, if the body has, rather conveniently, been burned on a boat in Utah. Here’s the thing: I can change the future so long as the future has not already been established as part of my own past. I can’t rescue Amy and Rory because I already know that I didn’t.
But what do I know about Trenzalore? There’s a big monument that looks very like my TARDIS. There’s a temporal fissure leading to my timeline. Maybe it’s my grave. Maybe, one day, it’s my burial ground. Maybe it is something else entirely, and we got it all wrong. Don’t know. Don’t plan to find out for as long as possible. The main thing is, Clara still jumped into my time stream, and ended up helping me through all of my life. All that is established, unchanged – but there’s wiggle room!
Or, put another way, "Wibbly-wobbly, time-wimey." Still, though, Doctor. Couldn't you have gone to Jersey and had Amy and Rory take the ferry?
(via Radio Times)