Flight plans must be issued by the flight planning office, as evidence to get back airside...it doesn't matter that you've already filed them yourself.
Very true; however if you have filed it yourself (via the internet etc) then get a printout of it from the GA office (or whichever office has the "computer" on the desk) and carry it around very conspiciously.
3rd world countries love nothing more than somebody carrying an official piece of paper
