Suspension of disbelief
Sheriff Purdy easily assembles a large mob of gun-toting men around him, and they all, without exception, believe his story that the kids used witchcraft to make his raincoat dance around and attack him. Then the mob was unquestionably committed to hunting and possibly killing the two kids based on that story.
Tia and Tony are recollecting their memories and suddenly claim they must be from another world, with two suns, because of the design on Tia's star case. Then Jason calmly concludes that they came here in a space ship.
The kids at the orphanage see Tony fly and make a baseball bat and glove fly. They don't seem phased. Truck (the bully) just gets mad at them for it.
Apparently aliens look exactly like humans and are biologically right at home here on earth.
It shows that an audience will go along with just about anything if it's part of a fun story.
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