Factual error: Early in the movie when the interior of the downed aircraft is shown (underwater in Chesapeake Bay), with the eerie picture of Dutch's wife and the congresswoman's husband sitting underwater in first class with their hair waving slowly in the current, they are shown on the right side of the aircraft (the left side as we are looking at them, but the right side of the plane proper). Yet, when the airline representative is discussing this "problem" (non-married-to-each-other people apparently flying as a couple), they are announced as sitting in row X (don't remember), seats A and B. Aircraft seating is always done from left to right - i.e., the A and B seats would be on the other, or left, side of the aircraft.
Continuity mistake: In the scene in DC, when Kay is walking in the park and encounters Dutch on the bench, we see a man in a black shirt with red lettering walk by twice behind the shots over Dutch's shoulder. You can also see the man at a further distance in the background and then closer on the next shot.
Kay Chandler: You know those drugstore kits that tell you when you're pregnant? They should have one that tells you when you're sane.