Continuity mistake: When the file with the photo of Amy's arm lands in the circle, the thumb in the photo is above the 'T' in 'THIS'. A moment later, the photo's position has turned 180° so that the thumb in the photo is pointed the other way. (00:02:57)
Continuity mistake: When Craig enters the house and falls back when the cybermat is attacking him, his arms are down by his sides, breaking his fall. As he lands, he's suddenly holding the mouse so it can't bite him. (00:25:51)
Continuity mistake: When Amy and Rory are searching the darkened kitchen, the flashlight Rory holds switches hands between cuts when it starts turning on and off. (00:13:52)
Continuity mistake: When the Doctor finds Joe's corpse, he walks up to him and puts his hand on his shoulder. In the next shot, facing Joe, the Doctor is suddenly in a completely different position relative to him, behind him as opposed to next to him. (00:15:06)
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 after everything the Master's put him through hurts him more deeply than death would.
Captain Defenestrator