Again, the clips I saw comparing similar movies do mention and showed scenes like the La Grande movie, sure when looking at them now it looks insane (like really, a teacher falling for a kid in her school is very icky)
However, I have seen people remembering wrong scenes in movies and video games added to others movies and games (with very different characters) in faulty childhood or young memories from me and other posters in the SDMB.
In one memorably thread, a poster wanting to identify an animated movie completely discounted the movie where an actual laser bridge was used. Many posters did then do go to wild chases on the internet, but it turned out that I did remember that it was the movie that the OP discounted!
What you seem to forget is how the brain does remember things, it is usually not like a photographic memory, it is more like bits that can get jumbled together the older one gets.
The alternate ending to “Big” is a red herring. In early 1988 a telemovie was test screened in New Zealand, Canada and other countries using various names. This movie was eventually shown on US television with the name 14 Going on 30, but with an alternate beginning! The original beginning has been carefully covered up all these years. It is rumored to have used the same plot and character names in the first 88 minutes as later used in the movie Big. This original beginning has never been shown again but numerous people claim to remember seeing this movie in New Zealand, Canada, and occasionally some European countries. This is the real mystery, what ever happened to the original beginning of 14 Going on 30, and why was it covered up?