Great demo! The recreations were perfect, and the way the Black Lodge stuff was handled was really good. Also, some of the visuals and cutscenes were truly amazing, congrats! I have a few suggestions, and a possible glitch I have encountered.
(SPOILERS)
Suggestion #1: I would make the videos shorter. Not necessarily the intro or the credits sequence, those are okay, but the videos on the televisions around the hospital are way too long. I think it would be better if they were shorter, or just a couple seconds long, and maybe include the whole thing as a bonus, or split it into different parts around the final game.
Suggestion #2: Even if I did enjoy some of the cameos around the hospital, like the characters from Halloween, An American Werewolf in London or Chinatown, I believe since some of them are portrayed by very famous actors, it can be quite distracting and immersion-breaking. Stuff like the Life is Strange note fits well, but seeing Jack Nicholson or Matthew McConaughey is a little odd.
The (possible) glitch: I have played the demo twice. In the first playthrough, inside the Black Lodge, I went to the end of the corridor with the statue and examined it. After this, I turned to the right and when I tried going that direction the cutscene with the statue turning with a collar played. I finished the demo, and then played again to get the object hidden in the bathroom. In my second playthrough, I found the collar and used it on the statue, and then the cutscene played out. I believe the cutscene played when it shouldn't in my first playthrough.
But all these things are very minor, the demo was wonderful! Can't wait to see what you do next!