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)
Continuity mistake: When the Doctor meets Nancy, when she warns him not to answer the TARDIS' ringing (fake) door phone, in a shot facing her he's holding his jacket away from his chest, but in the next shot facing him that hand is empty. (00:06:55)
Continuity mistake: When Jack is scanning Rose onboard his spaceship during their conversation, he leans against a metal railing in front of The Pilot's seat twice, in two successive shots. (00:20:40)
Continuity mistake: During the Doctor and Nancy's conversation at her hideout, in shots facing her there is a bright circle of light cast on the wall to her left, which her shadow partially overlaps. In shots facing the Doctor where both him and Nancy are visible, the circle is gone, and Nancy's hideout is noticeably more dimly lit. (00:23:15)
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.