This is related to the recent escape of Carlos Ghosn from Japan. While we don't know the details yet, M. Ghosn allegedly boarded a private plane from a small airport near Osaka [and probably in a kind of "luggage"!].
In this event, it seems the private plane was aimed to travel internationally. But that brings the question anyway:
Would the pilot of a private plane be authorized to change their destination after take-off, and, more specifically, request to travel to a foreign destination, while initially, (before take-off) the plane was supposed to reach a domestic destination?
Probably not the case in this escape story, but since there is much less passengers verification on domestic flights, allowing the flight-path change (for a private plane) would make things much easier for someone (wealthy) who wants to evade a country.