The Family of Blood (2) - S3-E9
Revealing mistake: In the penultimate scene, with Tim Latimer helping an injured Hutchinson across a muddy battlefield at night, one of the shots is flipped - in the unflipped shots, Hutchinson has his right arm slung across Tim's shoulders, but in the flipped shot, it appears to be his left arm, and the two young men have switched sides. (00:39:45)
The Family of Blood (2) - S3-E9
Revealing mistake: The pyrotechnic mortars used in the destruction of the Family's ship are visible in the shots leading up to their detonation. As the Family run from their ship through the field, the mortars are visible against the branches behind them. Shortly afterwards, they detonate, creating the illusion that the invisible craft has exploded.
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.