The house depicted in the film was used for day scenes only. It was torn down after filming because it didn't meet local building codes. The rooms were duplicated on an L.A. sound stage for night scenes.
Robert Zemeckis consciously shot What Lies Beneath (2000) in the style of Hitchcock, if he had access to digital technology. Also, the heroine of the film is a blonde, which was a common trademark of Alfred Hitchcock's.
Throughout the film, Claire's eyes are blue. When Claire allows Madison to posses her body, her eyes become green. Director Robert Zemeckis used contacts to emphasize the eye color change from blue to green to identify a "change of character".
Michelle Pfeiffer stated in interviews that she was initially put off by all the technical aspects of the film, but eventually learned to embrace them. In the end the actress found the experience both educational and enjoyable.
According to the original script by Clarke Gregg, the scene with the Ouija board was started by Jody. Later she runs out screaming after the séance gets a little out of hand. The scene was changed for the movie in order to emphasize how much Claire thinks she is losing her mind.
The Crown Point Bridge appears throughout the film. It was located in Addison, Vermont, near D.A.R. State Park, very close to where the house was built. It connected Crown Point, NY to Chimney Point, VT. Filming closed the bridge for several days, causing problems for locals on both sides of Lake Champlain. The bridge closed permanently on October 16, 2009, after an inspection revealed serious deterioration. It was demolished December 28, 2009. Its replacement, the Lake Champlain Bridge, opened in the same spot on November 7, 2011.
The trivia items below may give away important plot points.
When Michelle Pfeiffer lies stunned on the floor and the murderer leans over her face, the camera seemingly cranes down underneath the floor to look directly up at her face. The effect was created by using a glass floor. The solid floor at the start of the shot is drawn in by computer. A glass floor is also used when she drops the keys later on.