Trivia: When everyone is walking through the hotel corridors shortly after the Doctor, Amy and Rory arrive, there is a brief scene where a PE teacher exits a room and starts berating the Doctor. Though never stated, it's implied that this is Rory's room. In The Doctor's Wife, when Amy and Rory are trapped on the TARDIS and are being taunted by House, he tells House that he had a PE teacher just like him.
Trivia: Steven Moffat was so busy on different projects, and the shooting of Series 6 was enough of a troubled production, that he only had time to write one draft of this episode, which is what was shot. Not only is it amazing that this episode turned out as well as it did given that there was only a first draft of the script, this also explains some problems people have with the episode's plot - problems that probably would have been removed had there been multiple drafts.
Trivia: Lynda Barron, the actress who plays shop assistant Val, previously appeared twice in the classic series: the singing narrator in "The Gunfighters", and Captain Wrack in "Enlightenment".
Chosen answer: 1) When Stephen Moffat took over he ignored a lot of what had been developed before (there is not in-universe answer). 2) It would have killed Rose, so the Doctor absorbed the energy. His body regenerated before the energy could do a significant amount of damage that would prevent regeneration.