There was a scene where Connie tells John her dream and she gets very nervous and scared about it. That scene can be incredibly terrifying, specially thanks to how real it actually seems like to someone who was starting to believe in everything that was happening.
The original book consists of the purest, Grade-A Nightmare Fuel. Whether you're frightened by Keel's idea that the universe is not just aware butactively screwing with us just for laughs, or at the depths of his paranoia, is up to the individual reader.
The sound of Indrid Cold's voice on the phone.
The voice coming out of the motel sink's drain.
The beginning when they're driving down the street, and the mothman crashes into their windshield.