When the young man is smoking on the stair, he is only wearing his underpants, the scene then cuts to his girlfriend taking a shower, then we see him back on the stair, smoking, and then he is wearing a t-shirt too.
During the scene when George is in the booth with Tara Alexander you can see in the reflection of the glass that he is holding the telephone receiver to his left ear, but when the camera is on him he is holding the receiver to his right ear.
When George slams an ax into his father's head, no blood gushes out immediately; a latter shot shows the head bleeding.
When Susan and Bob are sitting in the living room, she grabs her drink , but in the next shot it disappears from her hands and discontinuity of the shots is apparent.
When questioned at the crime scene, C.J. moves closer to mother at one point, but in the next shot he is farther from her.
During the throat slashing scene near the beginning, blood does not gush out rapidly and nonstop as it should.
During the decapitation scene, hands can be seen moving around and feeling the bleeding neck stump after the head falls off. This action in actuality would not be possible, due to the disconnection of the brain.
Obvious dummy during the climactic decapitation as the neck clearly opens up on the right side, even though the boy swings at it from the left side.
Obvious dummy head of George's father when he gets axed.
When George relives his memories and goes upstairs to kill, there is already blood on the wall at the top of the stairs, but nobody has been killed yet and only one bleeding is his father, and that's from his nose.
Corpse of the girl sitting on a chair can be seen breathing at the end of the scene.
When George is hacking the corpse of a woman, which is on his father, we get
another shot of the father and corpse is not on him.
According to his patient record displayed on the computer screen, George suffers from "schizophernia" (spelling error).
Before Tatum's walk down 42nd Street, the doctor's computer screen on his case reads "MILD AMNESIA" but the doctor says he has "severe amnesia"