When the lights go out, there is no light in the house except for something small to not leave the actors in full darkness, but in the next shot of the inside of the house, there is clearly more light.

When Emily is coming home from work, it's not night like in the previous and following scenes, possibly because daylight was needed to shoot those scenes easily.

When Katia is chased through the house, at the end of the first corridor Mikos is very close to her, but in the next shot she is able to get a good distance in a new corridor without a problem.

In the final shot of the slaughterhouse worker's death via reciprocating saw, the blade disappears from the machine.

When Mikos is killing the nurse, the drill exits at the other side of her neck without blood, clearly revealing it's not human skin but some kind of material.

When the babysitter is shown dead with a pick in her head, she is still breathing.

When the boy scares Emily, he let's out a growl which is clearly the growl of a full grown man.

When Mikos is trying to break into the room where Emily and Katia are, the door can be seen moving inwards as if it were open. Emily locked the door, so he would first need to break it to push it in like that.

When the slaughterhouse worker's head is being cut open, the skull seems to bend at the point of contact with the blade, as though a piece of actual meat was used for the close-up shot.

When Mr and Mrs Bennett drive away in Mrs Bennett's car, as they leave the driveway two members of the film crew can be seen reflected in the window of the car.

When Mikos is shot by the slaughterhouse worker, the wires which control the squib are clearly visibly taped along the outside of his pant leg.

When Emily is walking through the house after letting the boy run away, you can see light reflections in the camera.

The police detective is in a car with New York plates. He then loans a car to the Catholic Priest. It has Quebec plates. The medical equipment and stereo markings are both in French.

When the babysitter is killed, blood is clearly seen dripping on the floor. However, when Emily comes to the house, she enters, being confused by the open door. Mikos would not have had time to hide the body and clean the blood prior to Emily's arrival.

When Emily leaves Katia in the room and exits with scissors, she finds Willy and starts running to him, but gets attacked by Mikos. She would have seen him coming since she had a full view of the room while running to Willy.

The TV at the party shows the Steelers getting a large gain on a play, and immediately after shows the Steelers on defense.

The police officer says that no one will be out tonight, as they will all be watching the Steelers-Browns championship game. The footage at the party shows the Steelers and the L.A. Rams.