Continuity mistake: When Amy is being pulled into the ground, there's a shot of her arms where the Doctor's hand gripping her left arm is missing. (00:13:38)
Continuity mistake: Throughout this episode, Amy's earrings seem to disappear and reappear.
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.