I'm Not Buying that one Theory, But I Have My Own
So all over the internet, etc. people are guessing that Cameron dreams the whole movie. That Ferris Bueller doesn't really exist. They can provide some evidence for it, and I am strictly limiting the word "some". Still, it is one of the most popular theories about a movie today. I really think they're wrong, because John Hughes was not the kind of person who would make this kind of a movie with that purpose in mind. Sure, the story arc is really Cameron's and that's fine, but we're not going to be listening attentively to Ferris giving us leisure rules and breaking the fourth wall if he weren't real. I say it happens just like Hughes meant it.
If I were to give my own theory, I'd say that what probably happens is Ferris Bueller and the rest of the cast keep living this same day over and over. It's weird, I know, and there's no proof to back it up. I don't necessarily believe it completely myself, but I sort of get that vibe every once and a while that Ferris, Cameron, Sloane and the rest don't really know any other life but this same day. It's like their minds keep getting erased and they wake up not knowing that the new day is in fact the day they lived just yesterday. So sort of like 'Groundhog Day', only with them not being aware of the lack of change. Anybody agree?