There's a process that should be followed when a plane is ready to be boarded. You go through security, get your passport out, head through the check-in desk with your boarding passes, and then get on board.
Every step in that chain seems to have been followed here, but there's one thing missing. Quite a big thing, actually. Where's the plane disappeared to? Do these people intend to stay there until the plane lands, inches away from them? If so, that's a very bold move!