Continuity mistake: When the Doctor takes to the nightclub stage to ask if anything has fallen from the sky, he has his right hand and arm up and gesticulating. But in several other shots of him from behind, it is his left arm that is up and moving. (00:04:20)
Deliberate mistake: When Jack is scanning the gas mask people, he has a scanner on his right wrist. However, when he shows Rose and the Doctor his image of the Chula warship, the scanner is on his left wrist. The makers flipped the stretch of film, according to the commentary, to make the shot work. (00:37:45)
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.