Everyone is familiar with The Shining, Stanley Kubrick's classic with Jack Nicholson playing a man descending into violence and insanity. Great movie.
It turns out there is a greater-than-you'd-think number of people who believe The Shining is really about something completely* unrelated to the plot: the moon landing hoax or about the Holocaust or about the Native American genocide or something very different from the story. This way of looking at art is sometimes called "Immersion Criticism" and represents a philosophy that small, ancillary details "are infinitely more important than the surface dialogue or the superficial narrative. And it's not just a matter of noticing things other people miss, because that can be done by anyone who's perceptive; it's a matter of noticing things that the director included to indicate his true, undisclosed intention."
Here's one short example:
The following video is longer but much better as it has clips and not just still. I recommend watching a few minutes of this one.
You can read more about Immersion Criticism here.
*Apologies for using so many emphases.