Trivia: When the Doctor sends the banknotes flying out into the street, all of the notes have David Tennant's or Phil Collinson's (the producer) faces on them, with quotes from the Fourth and Tenth Doctor (like "no second chances - I'm that sort of a man"). The notes have since become collector's items, selling often for about 50 pounds each.
Trivia: The controller used for the Christmas decorations is an old Nintendo 64 controller with parts added.
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.