Plot hole: When Laurie and her friend see the Sheriff in front of the hardware store, he tells them someone broke in and stole "A Halloween mask, some rope, and a couple of knives." Without someone doing a complete inventory of the store, there would be no way to know the specific items that had been stolen, especially when they are such commonplace things as knives and rope in a hardware store.
Suggested correction: Simple, he watched the security footage.
Before shutting off the alarm? Store video wasn't really a thing in a small town store back then.
Continuity mistake: Laurie's hair keeps changing throughout the movie. Her hair changes from wavy to straight while she babysits the kids. It is wavy again when she is going to Lindsey's house, and straight again when she is running back to Tommy's house. It stays straight until Michael starts to strangle her,where it becomes wavy again, having been straight in the previous shot. It all ends with straight hair. Surely all of this could not happen in a matter of hours.
Deliberate mistake: The opening camera scene, that's supposed to be shot from Michael's POV as a child, is too high as noted that he's almost face to face with his parents at the end of the scene and then is only mid-chest up to the father when he removes the mask. The POV is also too high as he walks across the dining room and as he approaches his sister upstairs.
Continuity mistake: After Tommy breaks the pumpkin, he is now walking on the sidewalk without the books that he was holding before.
Visible crew/equipment: When Laurie tries to escape Michael from the kitchen, she breaks the glass. You can see a second hand break the glass in front of Laurie's.
Suggested correction: You are incorrect, but it's an understandable mistake to make because the scene is very dark. It's hard to see, but Laurie actually uses both hands to break the glass... she puts them together and then slaps them through the window in a quick, fluid motion. (If you go through frame-by-frame or in slow motion, it's much, much easier to see.) That's why you're seeing two hands. It's not a crew member's hand... it's Jamie Lee Curtis' other hand.
Revealing mistake: Lynda calls Laurie using a rotary phone yet doesn't even look at what she's dialing. And you can tell she's not actually dialing in the first place.
Continuity mistake: At the start of the film Michael smashes the window, later on at the school the window is intact.
Continuity mistake: Michael breaks the passenger front door window on the wagon when he takes car, a short time later when he's driving in town the window is not broken.
Audio problem: While Lynda is filing her nails just as Michael enters the scene wearing a sheet and glasses, the sound of her filing continues despite her pausing.
Revealing mistake: Towards the end, Laurie pulls off Michael's mask, revealing his distorted face, but as he pulls the mask back down, the distorted face is also a mask as you can see the seam around his neckline.
Visible crew/equipment: As Laurie heads up to the porch, the shadow of the boom is visible above the door.
Continuity mistake: Before Tommy breaks the pumpkin at the school in the background there are 2 kids, one with a hat holding something in his hands which disappears in the next shot.
Continuity mistake: After Laurie gets home and her room she leaves her bag and some books on the bed - they change position between shots.
Continuity mistake: When Bob and Lynda get to Annie's house he leaves the door of the truck open, but when Laurie is on the street the door is now closed.
Revealing mistake: When Michael cuts Annie's throat, notice there's no visible cut or blood at all. When your throat is cut blood is going to pour out.
Suggested correction: True, but the view we have is distorted because it's shown through the windshield in a dark garage. Blood most likely poured out, but we don't see it because of how it's shown to us.
In the documentary, John Carpenter specifically stated that he left out of the gore on purpose. He wanted to film the movie so that the viewer would have a "mental image" of the kills without all the blood. He wanted it to be left to the imagination of the viewer.
Continuity mistake: In the beginning of the film when Michael is walking through the house, the clocks have different times on them. After he walks by the clock in the living room, it says 9:40. Seconds later, it strikes ten times.
Suggested correction: This scene jumps ahead as Michael was in the living room waiting for them to finish having sex and the boyfriend to leave.
Plot hole: Since the station wagon from the asylum was stolen, it should have been reported stolen along with the escape of Mike Myers. So why was the sheriff department not looking out for the stolen station wagon? We see Myers driving that station wagon freely without being stopped, while wearing a mask in broad daylight.
Continuity mistake: When Laurie, Annie and Lynda are walking home from school, the part where Lynda walks to her house you can see the station wagon on the side of the road behind them. A few seconds later it has moved up the side of the street.
Continuity mistake: After Michael hides behind a hedge bush and Laurie and her friend go to investigate, the sun changes between shots.
Deliberate mistake: In the first scene of the movie, we soon realize that we are looking at a house from someone's point of view who has no trouble looking over a porch railing, about 6 feet above the ground. It's revealed later that he is a little kid, about 4 feet tall. John Carpenter deliberately filmed it that way to exaggerate the impact of his little kid killer reveal. Unfortunately, when the kid is standing outside the house with his parents, you can see he could never have looked over the porch railing.
