Ummm, your son is just repeating the story in the movie “The Santa Clause”... he didn’t make it all up on his own. I’m sure this is normal for a kid to fantasize about being/living in the movie that they just watched.
Your son's been through the trauma of a divorce. He's also being old that Santa and his reindeer visit all the homes on a sleigh being pulled by reindeer in the sky who visit all the homes in the world.
Let it go. Let it go for this year. He's believing what he's been told.
sounds like he watched the movie with Tim Allen in it. almost to the T.
Do not worry...your son saw the movie The Santa Claus with Tim Allen. Great movie for kids!! Watch it and see for yourself. It is literally a movie about a kid's parents divorcing, and one night the sun is having to stay over with his dad and Santa Claus dies after he falls off the roof and his father turns into Santa Claus in the kid goes to the North Pole and sees all the Elves and the reindeer Etc. So don't worry it's just a movie! You guys should watch it together!