Continuity mistake: At the beginning of the episode, the police are chasing the bus and they give the numberplate as "Whiskey nine four seven Golf Hotel Mike." That is W947 GHM, but later on when the flying bus comes through the rift in time/space, the numberplate is completely different. This is because whilst filming in Dubai, the original bus broke down and had to be replaced. (00:17:58)
Continuity mistake: When the Doctor finds the stolen cup inside Christina's knapsack, he's shown reaching for it twice, in the wide shot and the close-up. (00:38:40)
Continuity mistake: On the alien ship, when the Doctor is told the bad news about the bus, his hand with the phone drops to below chest level. Then it's suddenly at chin level. (00:32:30)
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.