I'm not completely up on my Classic Doctor stories, so I missed the Great Intelligence reference until it started showing up online, but I could have sworn the "adult" voice of the snow globe/GI was House (it was actually Ian McKellen, where House was Michael Sheen)
Writer Neil Gaiman disclosed in Doctor Who Magazine that earlier drafts of his script for The Doctor's Wife implied that House, the villain of that story, was actually the Great Intelligence. These hints did not make it into the episode as aired.
Yeah. So Eleven accidentally triggered an adventure for his Second incarnation!
The TARDIS narrowly avoids becoming engulfed in a web-like substance in space. It arrives in the London Underground railway system, the tunnels of which are being overrun by the web and by the Great Intelligence's robot Yeti.