Board Thread:The Reference Desk/@comment-69.125.134.86-20130401025854/@comment-6433721-20130403040355

The Pandorica was created by the Coalition, from an idea taken from Amy's memories. (And isn't the symbolism there just awesome?)

His walk back through time was him entering the crack - his timeline was being unravelled and he got to relive things because of that.

She brought both him and the TARDIS back when she remembered. As she had remembered, once they were back, that had always been there. (And yes, this is one of those things that's tough to get.) If she hadn't remembered, they would have always not been there.

Try thinking of it this way: you have two pieces of film running simultaneously next to each other, in a kind of flimsy projector. The left is history without the Doctor and TARDIS, the right is history with the Doctor and TARDIS. The projector was showing the film on the left. At this point, if you rewinded, you'd see the past of that film - no Doctor. When Amy remembered, the projector got knocked over to the right side track and the mechanism severed the film on the left. Now when somebody who came in late asks you to go back and replay it, you only see the film on the right. Doctor!

It's a slightly different film, but it's now the only one that we could have seen.

Ah, see, we still don't fully know what the plans of the Silence entail - there's still unresolved doesn't make sense yet stuff. Personally, I think they engineered the explosion somehow but that is TOTAL speculation.