bad alien movie with main alien having pumpkin for his head

[RedFox]

and on top of that he throws some weird pancake-like aliens that have large teeth

i remember the scene when one of those "pancakes" landed on the car window

the setting was rural, young people were at some lake/waterfall when those floating pancakes attacked them!

[akiratubo]

Without Warning

http://www.imdb.com/title/tt0081764/