Director Heitor Dhalia stated to Brazilian newspapers that he had no control over his movie, all the major decisions were made by the studio. He couldn't even meet actress Amanda Seyfried before shooting to rehearse and prepare her to the role. He almost took his name out of the project, but in the end decided not to.
When Jill is nervous getting into her sisters car in her driveway, as she looks around a black cat can be seen crossing the road behind her. The camera angle changes slightly and while Jill continues moving to enter the vehicle the cat is frozen in motion since the background is now a still photo.
Jill's neighbor tells her that the mysterious van was outside her house at 1:00am, but when she confronts the locksmith she asks him if it was there at 2:30am.
The address of the locksmith changes several times throughout the film and refers to locations in Portland, Maine - not Oregon: Jill's initial Google search shows it to be 789 NW Riverton, Portland, OR; the officer reporting it to Detective Hood states that Jill pulled a gun at a "locksmith over in Oakdale"; the police report regarding the incident lists the address as 651 Rivertone. Riveton is a street and Oakdale is a neighborhood in Portland, ME. Neither of them exist in Portland, OR.