So Bradbury and his work was neither mistreated by the studios, nor put through any changes different than any other writer, then or now. What he wrote, subject to the expected modifications but with remarkable consistency, actually ended up on screen and he received credit for it. And his tale about two treatments is misremembered piffle, borne out by his own words on the page.

I kinda like the "sheriff is an alien" twist; seems close to the Dana Wynter bit in the later BODY SNATCHERS. And having the spaceship get away as opposed to being buried is clearly the better dramatic choice. The whole goal of the aliens is to get away; you need to pay that off. Either way (buried or skedaddling home) has a note of ambiguity, but having them take off is a far better payoff.