Goofs

When Bonnie first goes to gene therapy, the scars are all over her back and down her left arm. However, when the four of them are strutting down the school hallway, her short sleeved shirt reveals no scars on her arm. The scars are back down her arm when she goes the second time to the doctor.

When Bonnie goes back to gene therapy she has bandages on, that weren't shown in any other part of the movie. They also extend up her neck, but scars are never seen on that part of her body, even when her hair is up.

The chest of drawers that hits Sarah in the final confrontation inexplicably disappears when Nancy is searching through the clothing.

Sarah's shirt through the climax of the movie changes from a ribbed pattern to a plain non-ribbed pattern.

Sarah's wrist scars are inconsistent throughout the movie.

The toilet door lock wouldn't work for a door swinging in that direction.

In the French class, the professor writes, "Si vous aviez faites vos devoirs, vous comprendriez." It should be "Si vous aviez fait."

In the opening scene, it is shown to be pouring rain when Nancy leaves the airport, and still raining when they reach the house. When they enter the house, they discover the roof is leaking very significantly; however, the floor is completely dry.

Robin Tunney's wig is obvious in some scenes, including the hair-changing "glamours" and during the climax after Nancy makes cuts on Sarah's arms.

The nurse tells Bonnie that they cannot make any warranties regarding results or side effects for her procedure. A warranty is a document assuring an item will be replaced if it breaks or does not function as intended. The correct word she should have used is guarantee; likely a dialog mistake by the actress.

When a female character is shown to later be in a psychiatric institution, she is shown with dishevelled hair and a striped prison uniform. However, her eyeshadow as seen earlier in the movie is still on.

Towards the end, when Sarah is walking through her dark house, two crew members are reflected in a mirror.

When Sarah walks into her room for the first time there is a shadow of one of the crew members behind her on the door.

Nancy Downs is very poor and living in a trailer, yet she goes to an expensive private school in Southern California.

In the French lesson, the teacher wrote on the board "Si vous aviez faites vos devoirs, vous comprendriez" (which means "If you would have done your homework, you'd understand"). Actually, it is supposed to be "Si vous aviez FAIT vos devoirs, vous comprendriez".