Factual error: Owen resuscitates Tommy using a defibrillator. The heart monitor shows a flat line, indicating Tommy's heart is not beating. A defibrillator has no effect in this situation. This is a widespread error in many films and TV shows.
Factual error: Martha picks up a bone saw to start the autopsy on Owen. An autopsy should start with a Y incision from just below the arm pits to the sternum and then down the stomach to the pubic region - using a scalpel, not a bone saw.
Factual error: Jack calls Gwen, and when Rhys takes the phone and hangs up on him, Jack's cell phone, for the second time in the series, sounds an audible, impossible dial tone. (00:13:00)
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