There is this fake documentary about earth on the brink of disaster. A huge asteroid was gonna crash but the government destroyed it or something. Everyone was happy but at the ending scene, the government people looked at the huge computer screen and saw hundreds more of the asteroids coming. this was probably 15 years ago. i was too young and i thought it was so realistic.

Sounds like Without Warning (http://www.imdb.com/title/tt0111735/)