How about the fact that when Big Al sees Max and David pull into his shop, he stops dead in his tracks and stares. He doesn't move an inch or stop looking, not even when he hands David some change or some tourists check out the ship. Only when the duo take off again does he speak.
"He just wanted to phone home."
The security guards in the spaceship hangar have to read an instruction manual on what to do in case of an intrusion.
"Does this leak?" "I don't not leak. You leak, remember?"
One of the alien creatures gets the NASA hat off of David's head. Then belches.