When i got back from watching the film, i was blown away storyline, certain things mades scence, but the more i try to get my read found it, the more messed up my mind gets. Anyway i wemt looked for info and heres a little something i found. http://www.donniedarkofilm.com/ its the link to the film website, its crazy. There are three 'levels' open to you but you need a password to access levels two and three. Go into level one and try to figure out what the password is, ive been at it for about an hour and a half straight. I does explain some of the theory behind the film aswell.
Have a go it will get you brains working overtime.