Actually, The only world building they did firmly establish was that the aliens did not matter…
For all the audience needs to know, they used the gas to transfer their consciousness into a new host, and they do this everytime they visit a new biosphere.
But no, you fucking de-cloak early during one childrens birthday party in South America and your ass is a joke, you get fucking anthropomorphized for the next 20 years…









But then who will protect us from those 20 guys with box cutters?
You remember, the ones they used as the excuse to establish the ministry of the interior.