Continuity mistake: When the Doctor starts writing "Time" on the chalkboard during class, the "T" is slanted, but in a following wideshot when he's completed the vertical "TARDIS" the handwriting has changed. (00:08:10)
Continuity mistake: After the Doctor tells Bill that nothing gets through the TARDIS doors, when she responds that they're made of wood and have windows, the Doctor's left hand changes position between shots from being apparently by his side to suddenly resting on the door. (00:28:40)
Continuity mistake: When the Doctor holds out his sonic screwdriver for the Dalek to scan, his grip on it changes between shots. (00:42:25)
Continuity mistake: When Bill says to the Doctor, "Do what you gotta do," he raises his hands to her. His hands are closer to Bill's face in shots facing him than shots facing her. (00:48:40)
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