When North is in Alaska, and the family is walking their grandfather to the shore, the ceiling of the studio that the scene is filmed in is visible.
When the lawyer, Arthur Bell, meets North for the first time on the street, he hands North his card and promptly takes it back. In the next shot, North is still holding the card. At that point, Mr. Bell reaches to shake North's hand (which is still holding the card) and in the next shot the card disappears again.
When North is being chased through a New York airport, he passes a neon eagle on the wall. This eagle is in the Los Angeles airport.