The Doctor, the Widow and the Wardrobe - S7-E1
Continuity mistake: When the Doctor asks the wooden people to show the Arwells where the timeship is going, the queen raises her hand, widening the window's field of view. In a shot shortly after focusing on the Doctor, the queen's hand is lowered in the background, before suddenly being raised again. (00:48:57)
The Doctor, the Widow and the Wardrobe - S7-E1
Continuity mistake: When the Doctor starts falling towards Earth with the spacesuit, the planet is noticeably smaller than it was when the spaceship he's falling from was arriving above Earth at the very beginning. (00:01:33)
The Doctor, the Widow and the Wardrobe - S7-E1
Revealing mistake: When Cyril is walking around the statue and chair in the tower, if you look closely you can see the statue's hands move or shake. (00:30:14)
The Doctor, the Widow and the Wardrobe - S7-E1
Factual error: Cyril is introduced looking at the Moon with a telescope... in a brightly-lit room through a window with the curtains mostly shut, circumstances in which he's not going to see anything at all. (00:03:56)
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.