I used to believe that the "million dollar movie" that used to run on NYC TV stations at 4pm was actually 2nd run features of movies that had already been shown to a select group of affluent people that literally paid one million dollars to view the movie.
It seemed odd to me that people would spend so much to see a movie before me, but then again, some of them were pretty good. (I think I held this belief because my older brother told me this was true -- nasty!)
A childhood belief about films

others believed things like this
- when i was little i believed that when we watched a movie people had to act the movie all over a gen.
— Emmer - I believe my mom had to pay like a million dollars for me to go to school— kelsorocksursocks
- I used to believe that the credits at the end of a movie was a list of people in that were watching it.— jon_
- I used to think that a movie is made in realtime. I tought that a 2 hour movie is made in 2 hours.— Alexander
- I used to think that when a movie was 'based on a true story' it was happening for real then and there— Tom
- I used to think that if a movie was advertised on the side of a bus, that meant it was really good. — Aretia