Although the stranger is played by Scottish-born actor Tommy Flanagan, the phone-call voice is actually Lance Henriksen's. Henriksen fit the voice, whereas Flanagan fit the stranger's build.
Though the film is billed as a remake of the same-named 1979 film, it's actually only a remake of the first 20 minutes of it--the ones that made it a cult classic.
There were at least five different versions of the peach/coral-colored t-shirt Jill wears throughout the movie; a special "waterproof wet-look" version was made for her to wear through her scenes with water.
The front of the Mandrakis house was built at an unused reservoir; the interior was in a studio.
Camilla Belle had to do two months of weight-training and learning how to run to prepare for the role of Jill.