Everybody talking about these glitches that disrupt the game and whatnot, we really, really, really, REALLY gotta remember that it's a demo. It's a 1.3gb download, hardly the full game, it's part of the game's code removed from the full product. If anyone has any idea how finicky coding can be, they realize that when you mess with one part in anyway, things can go wrong in another part. That's not to say that no bugs will be in the full release, but a chunk of code reworked for a demo is really not a good example of the overall coding of the final product :/
For the love of whatever deity you wanna pray to, take that into consideration. Seriously.