Continuity: When Kathy and George kiss on the bed, and in following shots, the mug on the desk to the viewers right of the bed constantly rotates itself, evident by the mug handle.

Continuity: When Billy is holding logs still for George to chop, the second log he puts on the stump is striped of any bark. But when George swings down to chop it, the log is suddenly covered in bark.

Continuity: When George is laying in the bath and two arms grab him, the hands are all slit around the wrist, but in the next shot they're not.

Continuity: When the realtor shows the Lutz's the bedroom, and hears a noise, she turns her head to look. In this shot she is in the living room, not the bedroom.

Continuity: When Kathy and George kiss on the bed, and in following shots, the blankets and bedsheets wrapped around George change.

Continuity: When George rips the phone from the wall, a long cord is attached to the back of it, but in the next shot only short frayed wires are on the back of the phone.

Continuity: Lisa’s finger becomes bloody, as Jodie puts it into her bloody hole on her forehead. However, between shots, Lisa’s finger becomes clean.

Visible crew/equipment: In the scene where Kathy is bringing in the groceries and she asks George where Chelsea is, they run outside to look for her. As the scene goes along it pans past the truck and you can see the reflection of the camera in the truck.

Revealing: When Chelsea is on the roof of the house and Kathy joins her, Kathy's hair is blowing in the wind, while Chelsea's stays perfectly still, the water in the lake is also perfectly still. Obviously the director had the actors do the scenes separately until we see them both together in which case both characters hair is blowing around.

Audio problem: When Chelsea is screaming "Liar! Liar! Liaar!!" to her mother, Kathy, in one shot we see Chelsea's mouth still saying "liar," but no audio is heard.

Continuity: When the Lutz's look around the house, they enter a bedroom. Kathy walks up to a window and looks out. In the next shot George walks up to the same window - the whole window is in shot, but Kathy has gone.

Factual error: After George and Kathy leave the Doctor's office they drive through town. When they are talking in the car there is a shot where, next to George's face, you can see the sign of the town hall where the scene was filmed, 'Village of Antioch' in Antioch, Illinois.

Continuity: When George locks the boat house door, you can see inside the boat house through the cracks in the door, but there is no boat visible inside even though there was a boat there in the previous shots.

Deliberate "mistake": In the beginning, the police chief says "The six members of the family were found last night, in bed, shot and killed." As he says this, look to the left of the screen. In the background, the real Amityville house (dark brown with white windows and trim) is shown instead of the house used in the rest of the film. That segment was from actual news footage of the murders from 1974; apparently, the director didn't want to recreate it.

Revealing: Ryan Reynolds is wearing red-eye contacts. You can see the whites of his eyes around the red circle of the contacts in several scenes - most noticeably, right after the home movie he's watching down in the basement melts.

Audio problem: When the realtor suggests turning the basement into “A game room. Or a play room,” her mouth says otherwise.

Continuity: When Kathy reprimands Chelsea for standing on the edge of the boat, the balloon Chelsea holds swaps hands.

Continuity: When Harry, the dog, scratches at the wall, a large slab of concrete laying on the floor, by the wall, vanishes.

Other: Towards the film end, when George climbs up stairs with the gun to kill others, he walks into the passage and shuts the door. A mirror is there in the passage, but there's no reflection of George in it.

Continuity: When the children and Kathy push the large wooden desk in front of the door, to barricade George in the basement, the items on the desk (cloth, doll, books,) repeatedly change position, disappear, reappear etc.