Continuity mistake: When Purcell is sinking into his carpet, just after a shot where he's shown having sunk into the floor up to his waist, we see a shot focusing on his dog where Purcell's legs are visible as he falls forward onto his hands, despite his legs having already been pulled under. (00:23:38)
Continuity mistake: When Alex is hugging George after rescuing him from the peg dolls, George's arms are down in shots facing Alex, but his left arm is up in shots facing him. (00:37:23)
Continuity mistake: When Amy and Rory are searching the darkened kitchen, the flashlight Rory holds switches hands between cuts when it starts turning on and off. (00:13:52)
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.