Continuity mistake: When the old man dies and Owen is trying to revive him, the position of the man's head changes several times between takes, from lying flat to propped up on the pillow and back again. (00:37:00)
Continuity mistake: When Maggie walks away from the car accident, the blood smears on her white gown change repeatedly from shot to shot. (00:16:30)
Plot hole: Owen is unable to give Henry the kiss of life as he has no breath, and yet he is able to talk.
Answer: He might have requisitioned or stolen it from Torchwood London, or he might have been ready down below once it'd been severed, searching for "the right Doctor" and not knowing that the newly-regenerated Doctor was the one he was looking for.
Captain Defenestrator