The Doctor wasn't even bothered about figuring out what was going on. He'd learned to take these things on trust a long time ago. There'd be a way out when he needed one.
There was one thing he was interested in finding out, though. He swung their hands a bit as he practically skipped towards the building in the trees and looked sideways at Jack. "What point exactly are you from?" he asked cheerfully. "Must be some time that first night, if you're still in that uniform?"