Matt's Unfinished Business

One of the reasons I was surprised at the announcement of Matt Smith leaving is that his Doctor still has some unanswered questions hanging around. Unless the next two episodes can answer them, they're going to be hanging around until the 12th Doctor era.

The most important question is who blew up the TARDIS in Series 5? Unless the entire fandom has missed the answer, we still have not received any information on what caused the TARDIS to self-destruct in The Pandorica Opens. I'm now starting to think Moffat is playing something extremely long-term here that won't show up until Series 8. Either that, or he hasn't caught onto the fact that we don't know, which I think is unlikely.

Another thing is the Doctor's screwdriver. He was supposed to get a new sonic screwdriver and give it to River the last time she saw him at the Singing Towers of Darillium. We already saw that scene in the Last Night mini-episode, but we haven't seen the Doctor get a new screwdriver. That has to happen sometime before the Christmas special, which really only leaves the 50th anniversary.

You can see a complete list of unanswered questions from Matt Smith's and David Tennant's time here. These two thing are just the main items left from Matt Smith's era.