Cullen and Peyton are said to be in seats 3A and B, which are on the left side of the plane, but their bodies in the submerged airliner are securely buckled in seats on the right side of the aisle.
When Kay arrives at the cabin, there is a motorcycle parked on her left as she exits her car. When she leaves, that motorcycle has become a large SUV.
Near the end of the movie, as Kay Chandler is talking to Dutch Van Den Broek, she kisses him in the cheek and leaves a lipstick smudge on his left cheek near his mouth. In the next shot of him, the smudge is gone.
Near the end of the movie, it's shown to be snowy, dark and extremely overcast outside the Capitol Building and other places in D.C. In the next shots, when Kay leaves her office for the last time, sunlight is streaming through the windows. When she's walking down the Capitol steps, it's overcast again.
When Kay visits Dutch in the hospital, her hair changes between shots.
When Kay receives the belongings of her deceased husband Cullen, the clothes bag and the leather briefcase are in pristine condition, though they have been in the sea for several days. It is also unlikely, that the gift wrapped jewelry case Jessica found from her father's luggage, could have survived in the sea without any visible damage.
When Dutch Van Den Broeck dials *69 to find out the phone number of the last caller he actually dials #69.
When Dutch and Kay are walking along the street in Miami, dolly track is seen between them in the background.
Dutch and Kay exit the airport, presumably either Reagan National or Dulles, upon their return from Miami. Dutch says something like, "I live in Northwest," referring to NW Washington DC. The Lincoln Memorial is behind them as they drive across Memorial Bridge, which means they are going into Virginia and away from DC, which is the wrong way.
The flight manifest for the crashed plane includes Mr. and Mrs. Cullen Chandler, which would indicate a U.S. Congresswoman was flying on that plane. While the airline care drew may have figured that out quickly, it is surprising it is not not brought up or noticed. Also, if she seeking to pass unnoticed, flying under a Congressman's name is a strange way to go about it.
The first time that Kay faces reporters, a mike is visible on white background.