A Good Man Goes to War - S6-E8
Continuity mistake: Rory threatens Madame Kovarian with a sword. It's on her neck, then in the next shot the sword is not touching her. (00:23:38)
A Good Man Goes to War - S6-E8
Revealing mistake: Several of the hallways in Demon's Run, particularly the one where Madame Kovarian has the baby brought to her and the one the Doctor's standing in when he realises where Amy and Rory's baby was conceived, are the repainted sets of the TARDIS hallways from "The Doctor's Wife", three episodes before.
A Good Man Goes to War - S6-E8
Audio problem: When Madame Kovarian says, "Give the order, Colonel Runaway," she is seen facing three-quarters away from the camera. Her jaw does not move as she speaks. (00:25:10)
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.