Yeah, the farthest you can go is on the top of the roller-coaster when after about a minute of travelling along it you get hit by a cart on the track in a cut-scene.
You could stay there as long as you wanted to, but you wouldn't have much to do there. It ends when you go down the roller coaster tracks. It would be neat if you could go further, but alas, Heather must wake up.
I prefer committing suicide by jumping off of the rail road tracks, something I always do to check out Heather's "omg my hair doesn't move at all" thing.
Also, video game suicides are fun! SUICIDES FOR EVERYBODY!!!