how can you tell these are aliens? let's take them individually, from l to r:
notice how the younger guy alien is sucking his stomach in so hard it might just come flying out of his behind. he doesn't know that it's okay to let it hang, i guess.
the older guy alien clearly forgot that if you don't adjust your bald-head wig properly, the absence of anything underneath shows up rather obviously.
woman alien #1: the blinding blue jacket might function well as a reflector on the sun, but down here on earth, all it reflects is a deer-caught-in-the-headlights dumb gaze and the photographer's flash in her midriff.
as for woman alien #2, it looks like she was in the middle of putting on some more foundation (mostly on her forehead) and the camera caught her off guard. oh, and in the process, her 30-lb hand baggage slipped from her firm grasp.