"The Nightmare" is the kind of movie that isn't as interesting to watch as it is to read or think about. I believe the direction is what undercuts it; moments don't have the impact they should have. Scenes could have been shot and handled better, but with the wobbly camera, the director himself feels like just another stoned bystander among the movie's teenage ravers.
The story is about a party girl who is apparently hit by a car. She survives with no visible injury, but begins to have visions of a creature that looks like a cross between Gollum from "Lord of the Rings" and Dobby the House Elf.
The people around her believe that she is going crazy, and perhaps she is.
There are several sequences that appear to show the movie rewinding itself, perhaps as an indication to us that the movie is not occurring on a linear timescale. It may also be telling us that the events we just witnessed are the culmination of what we are witnessing again in the rewind sequence.
The problem is that the movie doesn't have a sure hand at the controls. It's too disjointed to make you really curious about what you're seeing. The concept is interesting enough, however, to recommend it to students of the weird.