About that "poisonous gas"
In the sequence when Roy and Barry's mom arrive at Devil's Tower they learn about hazardous gas leak and quickly determine it's a hoax by the US Govt to scare away civilians. We as an audience believe Roy's skepticism as well. Then later as their driving down the road we see livestock scattered along the roadway BUT in a clear as day shot we see the camera pan over one of the animals and we can see it was fully breathing like it was asleep.
So was it a hoax and the animals were just given tranquilizers or were they killed on purpose?
Secondly, when Roy, Barry's mom, and a third Encounter witness scale Devil's Tower the Feds start spraying them. Did I miss an explanation scene because I was confused by this as the 3rd guy doesn't make it and gets gassed and we also see its effects on birds. Was he killed or was this the same gas used on the livestock earlier?