The Time of the Doctor - S7-E17
Continuity mistake: After the Doctor yells at Handles for putting him on the Dalek ship, the Doctor grabs him and carries the head with his right arm, then switches the head to his left arm. However, in the close-up as the Doctor asks, "What does this question mean?" we see Handles is back on the Doctor's right arm, but next shot as the phone rings, Handles is carried on the Doctor's left arm again. (00:01:56)
The Time of the Doctor - S7-E17
Other mistake: While looking around the Doctor's room, one of the children's drawings Clara passes by has the TARDIS in it... when the TARDIS has been absent for all of the 300 years the Doctor has spent on Trenzalore up to this point, so none of the pictures existing now should have the time machine present. And it's not a particularly weathered picture, either, suggesting it can't be from the beginning of his stay on the planet. (00:31:47)
The Time of the Doctor - S7-E17
Continuity mistake: When the Doctor teleports onto the Dalek ship and announces himself, he's holding up a broken Dalek eyestalk in the wide shot as he throws off his hood, but then in the close-up he throws the hood off again, with his arm lowered. Then he raises his arm again, with his arm bent at the elbow, only for a wide shot to have his arm sticking straight up, with his elbow straight. (00:00:55)
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.