Factual error: When they first pick up the Mona Lisa, they show the back. There you can see a canvas sheet over a wooden framework. However, the Mona Lisa is painted directly onto wood, no canvas at all. The scan they run even says it's painted onto wood, despite visual evidence to the contrary.
Continuity mistake: The photo of Cleric Partridge with Mary O'Brien is crumpled and folded when we first see it in the morgue and when Cleric Preston shows it to O'Brien. However, when Preston is sitting at his desk and looking at the photo by himself, closeups of the photo show it as smooth without the signs of wear and tear seen previously.
Mary: Let me ask you something. Why are you alive?
John Preston: I'm alive... I live... To safeguard the continuity of this great society. To serve Libria.
Mary: It's circular. You exist to continue your existence. What's the point?
John Preston: What's the point of your existence?
Mary: To feel. 'Cause you've never done it, you can never know it. But it's as vital as breath. And without it, without love, without anger, without sorrow, breath is just a clock... Ticking.
Question: After Preston kills DuPont, there is no blood or wound on his neck. Only moments later, he goes to destroy the Father broadcasting room, and suddenly there is a cut on his neck with blood on his collar. Is this a mistake, or is it implied that he fought more and got injured between DuPont's office and the broadcast room?Quantom X