I have the ability to take screenshots.

http://img205.imageshack.us/img205/2709/vlcsnap2010062015h15m33.jpg

That picture is of the house from the outside, as seen in The Eleventh Hour. The following picture shows the stairs on the third floor, and the little door they lead to, from the same episode a few moments later.

http://img341.imageshack.us/img341/2237/vlcsnap2010062015h17m06.jpg

You have to look close to see that it's a door-thing at this size, but my screenshots don't take any larger.

... come to think of it, look at Prisoner Zero's door in that shot. It's the one directly behind Amy's hand, yes? With another door to the left of it?

If so, how does that work? When Amy went into Prisoner Zero's room, the room opened up to the left ... directly into the space where that other door should lead. That one could easily be a simple production error, but I'm in full blown paranoia mode now.