Continuity mistake: At the beginning of the episode, the police are chasing the bus and they give the numberplate as "Whiskey nine four seven Golf Hotel Mike." That is W947 GHM, but later on when the flying bus comes through the rift in time/space, the numberplate is completely different. This is because whilst filming in Dubai, the original bus broke down and had to be replaced. (00:17:58)
Continuity mistake: When the Doctor finds the stolen cup inside Christina's knapsack, he's shown reaching for it twice, in the wide shot and the close-up. (00:38:40)
Continuity mistake: On the alien ship, when the Doctor is told the bad news about the bus, his hand with the phone drops to below chest level. Then it's suddenly at chin level. (00:32:30)
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