Someone directed me to a Cracked.com article, which had this to say about the movie "Radio Flyer":
There are a couple theories floating around here. One is that the younger brother is a mental fiction created by Elijah Wood's narrator to cope with the abuse--it's notable that no one except the narrator's family interacts with the younger brother. Another theory (which even Roger Ebert suggested) is that the younger brother plummets to his death or is beaten to death by his stepfather.
--
6 Insane Fan Theories That Actually Make Great Movies Better | Cracked.com You know, I always figured either the brother died, or at the very least it wasn't the younger brother who was being abused, but the older brother. I figured something about the narrative had to be untrue, because of the way Tom Hanks wraps up by saying that's the way he prefers to remember it.
And as for other insane theories I think make movies better, I've said before that I think "Donnie Darko" makes perfect sense if you assume that Donnie is insane and has a premonition of his death, and the bulk of the movie is his fantasy between the moment the engine falls off the plane and the moment he dies.