The FBI officer who was chasing Frank, and was the main inspiration for "Carl Hanratty," was really Joe Shea. Frank Abagnale Jr. used the pseudonym "Sean O'Reilly" in his book because Joe Shea was still in the F. B. I. He has since passed away.
When Carl is shown Frank's yearbook photo, the closeup reveals that the photo is printed using the scatter dot pattern typical of a modern ink-jet printer, rather than the halftone dot pattern of printing processes of the day.
Toward the end of the movie when Frank is walking in the corridor tube at the airport there are a couple American Airlines flights announced in the background. This was in the TWA terminal. It's possible that the filmmakers did this intentionally since American bought TWA at the time the movie was filmed, but in the late 60's there would not be an American flight in the TWA terminal as they were fierce rivals.