I have no idea why I didn't connect The Great Intelligence to the Snowmen until this episode. I knew the voice sounded familiar in the other episode, but it just didn't click. *sigh*
Oh well. I liked this episode. My mind is swimming with questions about John Hurt. I think, like others, he's a pre-doctor-doctor, based on what was said. He could also be the Time War doctor, but for now I'm leaning towards the former.