Plot hole: Those people created for medical experiments cannot run. In fact they can barely walk, so how come they can climb nearly as fast as Rose? What's more, when you see them climbing, they seem to have little ability to coordinate hand over hand. Even with the delay brought on by the cat-woman-thing, they should not have been able to keep up with her.
The Impossible Planet (1) - S2-E11
Plot hole: The Doctor and Ida are stranded 10 miles down, and yet the lift travels very slowly, like walking pace. They only have an hour's worth of oxygen left in their suits - by the time they get to the surface, it would have run out.
The Impossible Planet (1) - S2-E11
Plot hole: The rocket flew down a gravity funnel and (presumably) crash-landed on the planet, since the true Captain died during the landing. The rocket is big, but surely not large enough to contain all the 'flat-packed' materials for the sanctuary base (which is massive) and the gantry which supports the rocket. Where did that gantry come from? It is the same size as the rocket. It is not possible that the sanctuary base and rocket gantry could have fitted on board that rocket.
Chosen answer: The Master knows that deep down, he deserves death for the crimes that he's committed throughout his life, and since he regards The Doctor as his arch-foe, he expects it to be at his hands. The fact that The Doctor is still willing to forgive him for all of his crimes hurts him more deeply than death would.
Captain Defenestrator