Stanley Kubrick is considered by many to be one of if not the greatest filmmaker of all time. 2001: A Space Odyssey, A Clockwork Orange, Barry Lyndon, Full Metal Jacket, etc, Kubrick is at once a creator of mesmerizing pieces of smart entertainment and confounding puzzles. After you get past the veil of imagery for the sake of entertainment, you realize there has to be something much larger going on; in fact, there must be many different things going on. And Kubrick was known for being extremely detailed and controlling of his mis en scene and every aspect of the image in the same way that Alfred Hitchcock is notorious for. As one of the interviewees for the documentary Room 237 mentions, there are photographs of Kubrick personally arranging cans of sauce on a shelf in a storage room that forms the backdrop for one shot of Jack Nicholson in The Shining. That's the level of control Kubrick reportedly took with his films.
Thus, the floodgates for interpretation and speculation are flung wide open and come sweeping down just like the wall of blood down the hotel hallway in The Shining. Room 237 is the construction of detailed theories from interviewees regarding Kubrick's intention in this film. I will not go into great detail on these theories (for that, you'll have to watch this extremely interesting documentary), but suffice it to say that they involve portraying the Holocaust, the genocide of Native Americans in America and the white man's destruction and oppression of other races, the faking of the Apollo 11 landing on the moon, and several others. Each interviewee pinpoints a number of different scenes, shots, or details in the mis en scene that are quite convincing. Other examples are more of stretch and not so convincing, but as can be seen in the picture I included, little Danny just happens to be wearing a sweater with the Apollo 11 rocket on it. This is just one of the many, many pieces of evidence sighted for all sorts of theories. As the documentary ends, one of the interviewees (the one I found most thoughtful and self-aware), reflected on how such extreme speculation into a work of art like The Shining can lead into a sort of madness akin to what Jack Torrence (Jack Nicholson) experiences in the hotel.