Trish picks up the coffee pot (which cracked on the "hot" stove) with her bare hands.
When Coach Jana arrives home from school, her friend drills a
peephole through her door. The hole in the door is rough and ugly, yet in the next shot it's neater and has gained a metal eyepiece.
After the pizza man is discovered dead, Kim puts the phone
down on the desk before running into the living room. While Coach Jana waits on the line, it goes dead. In the next shot, Trish picks up the phone and speaks to an operator just before Russ Thorn cuts the phone line.
In the shot where Russ Thorn watches as Kimberly and Jackie walk up the steps to Trish's porch, Kimberly's hands are empty. But when she enters the house, she holds up a case of beer in her right hand.
When Russ is about to kill the phone repair woman, he pushes her face to the side, as if to drill into the side of her head. But when we see her dead body, the wound is dead center of her forehead. Also, the drill wound has no depth or damage and just looks painted on.
When the three girls go into Trish's kitchen after hearing the noise in there, the stove comes into view and all the burner knobs are in the vertical 'off' position, yet the noise they had heard was the glass coffee pot breaking because she had supposedly left the burner turned on. All the burners were clearly turned off.
When a character is making Kool-Aid she uses the larger packet which includes the sugar already added. And yet she adds her own sugar to the mix.
When Coach Jana hits Russ Thorn with the fire poker, it bends
like it's made out of rubber.
Russ Thorn emerges from the swimming pool, but when he attacks the girls seconds later, he is not wet.
When Courtney closes the refrigerator door in Trish's kitchen, you can see the actress playing the supposedly dead Kim pulling her weight up with her right arm so that her "corpse" won't jam the door.
When Neil gets stabbed to death, you can see that the knife blade bends.
When Russ Thorn is walking towards Linda in the high school hall, you can hear Linda's scream before she visibly screams.
When Russ Thorn leaves after inspecting a closet (where Trish is hiding), the camera's silhouette can be seen.
When Russ Thorn walks into one of the bathrooms' and looks at himself in the mirror, a glimpse of the cameraman's hand is reflected on the mirror. This is corrected in the Blu-ray version.
After they discover the dead Pizza Man, Trish gets onto the phone to call for help. It switched to a shot looking through the window, showing Russ outside, watching them. However, as the camera pans past these windows, the reflection of a second man is seen.
When Coach Jana arrives home and bends down to put her bag on the floor, you can see some equipment moving in the glass frame of the photo - on the shelf - above her.
(about 49 min.) Camera briefly reflected on the knife that Trish wields.
Trish had a knife in the room where Russ attacks her and Kim. She had dropped the knife but eventually knocks out Russ with a baseball bat. Instead of killing or severely injuring Russ (which she must have been prepared to do since she had a knife earlier), she and Kim try to remove the barricades to the door and escape. At minimum, Trish could have easily taken Russ' knife and broken both his hands with her bat.
Mistake 1: During the basketball scrimmage, when Valerie airballs her first shot, another girl on her team catches the ball right under the basket. Instead of trying a relatively high-percentage bank shot, she passes the ball over three defenders to another teammate in the side-court. Mistake 2: the coach doesn't criticize the girl under the basket for not taking the easy shot.