Continuity mistake: Throughout the episode, the collar of the Doctor's shirt frequently tucks in and out of his coat from shot to shot. Especially noticeable in the scenes where they are looking for and subsequently fix the Dalek's radiation leak.
Continuity mistake: When Colonel Blue informs the team that radiation levels are getting dangerously high as they head for the Dalek's trionic power cells, the team's location inside the Dalek, shown on a computer screen, changes between shots. (00:25:16)
Continuity mistake: During Clara's first conversation with Danny, the folders in her hands are unmarked in close-ups, but have labels on them in wide shots. In addition, the folders and newspaper she's holding keep changing position between shots. (00:07:30 - 00:08:26)
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