Corrected entry: Sylvia's badge has a 2006 expiry date at one time and a 2007 date at another. Granted she could have renewed it, but that is convoluted. My first thought it that it was a clue, but obviously not.
Corrected entry: The safe room is locked by a swipe-card, so why does Penn use an old fashioned key to gain entry? It's awfully lo-tech, and indicates that the room could be breached with not much force used against the door. Also, the safe room has magnificent panoramic views through the floor-to-ceiling windows. Even if they are bullet-resistant, big panes would still shatter or at least move, especially if an RPG or explosive were used.
Corrected entry: At the end, Nicole Kidman is talking with Sean Penn. She no longer has any scratches on her face from the bust bombing only a day or two earlier. In the previous scenes, she still has these scratches. There are conversational remarks that everything has happened over the course of nine days when they first met. These scratches would have have healed completely in only 2 or 3 days.