Continuity mistake: Throughout the episode, the collar of the Doctor's shirt frequently tucks in and out of his coat from shot to shot. Especially noticeable in the scenes where they are looking for and subsequently fix the Dalek's radiation leak.
Continuity mistake: When Colonel Blue informs the team that radiation levels are getting dangerously high as they head for the Dalek's trionic power cells, the team's location inside the Dalek, shown on a computer screen, changes between shots. (00:25:16)
Continuity mistake: During Clara's first conversation with Danny, the folders in her hands are unmarked in close-ups, but have labels on them in wide shots. In addition, the folders and newspaper she's holding keep changing position between shots. (00:07:30 - 00:08:26)
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.