Have we seen a news report yet about how Snowden traveled to Hong Kong? His choice of destination may have been dictated by where he could fly on a nonstop airline flight from Hawaii, where he was last based. His travel documents, because he was contracting for the NSA, may already have had restrictions on which destinations he could fly to. (Such restrictions have been routine for NSA employees for more than a generation. Airlines check travel documents before you board a plane on an international flight, because the airline is responsible for returning you at no charge to you if you are denied entry for lack of proper travel documents at the border of your destination.) He may simply have had no better choice when he had opportunity to leave work and leave home.
A few years ago I was cutting it close for a flight from New York to Maine. Everyone else had boarded when I got to the gate. When my wrinkled, self-printed boarding pass threw error noises, the agent told me just to go, "and run!" I breathed a sigh of relief when I was on the plane, but puzzled that a French tourist was in my seat. When we saw that both our tickets had the same seat we called over a flight attendant. "Wait, where are you flying?" she asked. "Portland, Maine?" With this comment I now fully understand the terror came to her face as she exclaimed, "This plane is going to Paris! Sir, you have to get off this plane immediately! Run, sir, run!" They shut the door behind me as I left.
So yes, always double check your gate assignments at the airport, as they may have changed.
>>Airlines check travel documents before you board a plane on an international flight, because the airline is responsible for returning you at no charge to you if you are denied entry for lack of proper travel documents at the border of your destination.
This explains the sometimes seemingly draconian photo ID checks by airlines at the gate. Thanks for clearing this up -- I didn't realize that the return cost was borne by the carrier. Makes much more sense.