At the beginning of the movie Michael is supposed to be 6 years old. However, when he is walking around the house you can clearly see that the scene is being shot by an adult. The camera is well above the door knob and when he goes outside he is as tall as his parents. Then they take the mask off and the view switches to the long scene, notice how much shorter than the adults he is.
(at around 14 mins) While in the company of Tommy Doyle, Laurie places the keys to the Myers' house under the mat at her father's request. Tommy says goodbye until later that night and Laurie starts singing to herself walking down the street. Michael Myers then watches her, breathing heavily but the motions of his chest and shoulders rising and falling do not match the sound.
Annie moans about having to babysit at the Wallaces' house, and Laurie says she's babysitting at the Doyles' home which is three houses down. Later in the movie the Wallaces' house is shown to be across the street from the Doyles'.
(at around 51 mins) When Annie brings Lindsey Wallace over to the Doyle house, she tells Laurie that she will just have to call Ben Tramer "tomorrow." In actuality, Laurie could just talk to Ben at school, as November 1, 1978 was on a Wednesday.
(at around 4 mins) When Michael Myers, as a child, walks through the living room with the knife, the clock above the stove shows 9:25 and the clock on the wall reads 9:40, but just 5-7 seconds later, the clock chimes 10 times.
When Annie is first shown spilling something on her clothes and takes them off to wash them, her panties are a solid color. Later when she is in the laundry room her panties have flower prints on them.
(at around 43 mins) When Michael is watching Annie in the kitchen he knocks down and breaks the plant hanging in front of the door. Later when Laurie approaches the same door (at around 1h 13 mins) there is a plant hanging in front of the door.
(at around 1h 28 mins) At the end of the film, there are shots of the interior of the house as it appeared after the events. One shot is taken from an earlier shot because the knife used in the last scene is still sitting on the floor of the living room.
When Laurie walks to the Myers house to drop off the key, she only has a few blocks to walk. However, when she and Annie drive clear across town to reach the Doyle house, the Myers house is conveniently close by.
When Annie and Laurie are walking home after school, Laurie spies Michael Myers standing by a hedge - it is clear he is wearing his signature white Shatner mask. Later, Laurie gets home and looks out of her bedroom window to see Michael Myers near a clothes line in the back garden looking at her - it is clear that he has on his striking signature mask yet again. What is clearly at least an hour later (if not more), Annie picks Laurie up to take her to their babysitting jobs for the night and while they are on the road, they spy Annie's father (the sheriff) who is attending a hardware store robbery where a mask and some rope had just recently been stolen - the alarms are still going off as Annie parks nearby to talk with her father. This time line makes no sense as the robbery would had to have occurred at least an hour previously for Myers to have had time to follow Laurie and have the mask for her to see him wearing it so it would make no sense for the alarms to still be going off and for the police to have just arrived at the scene.
(at around 24 mins) When Laurie and Annie are walking down the sidewalk and Laurie sees Michael standing next to a bush, from Laurie's point of view the bush is trimmed and neat, but when Annie walks up to the bush, it's all bushy with leaves sticking out everywhere.
(at around 1h 23 mins) When The Shape attacks Laurie while she is hiding in the closet, the position of the clothes, as well as the types of clothing hanging in there, change frequently, and in every shot of the closet afterwards.
(at around 23 mins) After Lynda says goodbye, Laurie and Annie continue to walk home from classes together and the following scenes show that the takes were combined from different periods of the day. When Laurie sees the Shape peering at them behind the bushes, the Sun is setting behind the houses to their left. In the very next scene when she tries get Annie's attention, the Sun is shining on them from directly above. When Annie rushes to confront the Shape the Sun is still setting but once Annie departs, it shines completely overhead again as Laurie is frightened by Sheriff Brackett.
Whenever Laurie, Tommy or Lindsey looks out the window at the Wallace House, there is a pumpkin visible with a candle burning. In all of the shots except two, the jack-o-lantern is a flat-looking thing. The two exception shots show a tall and more narrow/skinny pumpkin.
(at around 19 mins) After Doctor Loomis has talked to the Sheriff from a phone on the highway and warned him about Michael, he notices a red pick-up truck and walks towards it to inspect it. We can hear the noise from the train that is coming towards the camera on the left side, shows up and starts to pass. The next shot, is from the opposite side, showing the Doctor and the truck from the front. We still can hear the train passing but there is no train in the background.
(at around 5 mins) After Judith's boyfriend leaves, young Michael ascends the steps to his sister's bedroom with a kitchen knife in hand. Her clothes are balled up together in a pile on the floor at the top of the landing. After he picks up the clown mask from the ground and puts it on, the pile of clothes are now trailing piece by piece towards Judith's bedroom door and one of the articles, a pink sweater, is now openly lying flat.
(at around 29 mins) When Annie and Laurie are driving in the burgundy 1977 Monte Carlo, the rear view mirror changes from being perfectly straight to being crooked. Almost every other scene the mirror is the opposite of the scene prior.
(at around 17 mins) After Tommy's bullies cause him to drop his giant pumpkin, they all laugh and run away out of frame in the direction of the school's back lawn. In the next shot, though, only two of the boys run across the grass and the last one runs straight ahead and down the steps before bumping into Michael Myers.
(at around 50 mins) After Lindsay agrees to Annie's suggestion of watching the horror movie with Tommy at his house, they immediately leave with a throw and a bowl of popcorn. The TV was left on and the cushions and a newspaper on the couch were disturbed. When Annie returns for her car keys the cushions and newspaper are propped up neatly, as well as the TV being completely turned off.
(at around 1h 18 mins) Being chased by Michael Myers, Laurie finds herself trapped in the kitchen by a rake blocking the exit and brazenly breaks a glass pane to get away. The shards are angled jaggedly in the frame when she pushes her hand through the opening, but when the camera shows another angle of Laurie pushing the rake aside and running out the broken glass is completely missing.
(at around 1h 16 mins) When Laurie investigates the upstairs bedroom of the Wallace residence she pushes the door wide open before finding the bodies of Annie, Lynda and Bob. When she runs out into the hallway in shock, the door is only partially ajar.
When Laurie first arrives home from school, she glances out the window and sees Michael standing in her neighbor's yard. It is very windy. But in the next moment, she slams the window shut and the trees are perfectly still.
(at around 25 mins) As Laurie is walking home from school, a leaf (or some other debris) is briefly seen stuck in her hair. When she turns back, looking towards where Michael was after she bumps into the Sheriff and is startled, the leaf is gone.
(at around 10 mins) Toward the beginning of the movie when Michael is attacking the woman in the car, she steps on the gas turning the car toward some trees. In the next scene when she jumps out of the car, Michael jumps in and drives off. The trees aren't there anymore and he's driving straight on a road.
(at around 24 mins) When Annie is by the hedgerow telling Laurie that the person who has been following them wants to talk to her, a puff of John Carpenter's cigarette smoke floats into the shot. (This was pointed out by Carpenter during the film's audio commentary)
(at around 19 mins) When Dr. Loomis is talking in a phone booth after Myers escapes ("It's your funeral!"), when he exits the booth and notices the abandoned truck, a crew member is reflected in the glass of the phone booth.
(at around 47 mins) While Lindsey is watching Forbidden Planet and is alone in the living room, the camera dollies across the couch. A large shadow moves across the couch from out of shot but no one should be in the room with her.
(at around 1h 20 mins) When Laurie runs back into the Doyle house after being chased by Michael, she notices the living room window is open. When you look closely you can see a fan that is being used to blow the curtain.
(at around 1h 18 mins) When Laurie is trying to escape the kitchen during the initial Myers attack, a small light with blue gel to simulate moonlight is seen in the left side of the frame. (widescreen only)
(at around 1h 17 mins) Just after Laurie, played by Jamie Lee Curtis is slashed on her left arm by Michael's knife, she turns around screaming and then falls backwards over the stair railing to the landing below. If you watch closely when the camera shows her falling over the railing with her legs pointing upward, a harness with a rope attached can be seen around Jamie Lee Curtis' left wrist/arm as to prevent her from really falling down to the first floor.
(at around 20 mins) The scene that shows Laurie, Annie and Lynda walking home from school starts with them walking from a school with outside lockers. Schools with inclement weather, such as Illinois, do not have outside lockers.
When Lynda and Bob pull up to Lindsey's house, you can clearly see a California license plate on the front of the van. (blue with yellow numbers). Other vehicles in the film have the proper Illinois plates (white with black numbers).
(at around 19 mins) You can clearly see the mountains in the background, when Dr. Loomis is on the phone and sees the Rabbit in Red matchbook. Since this movie takes place in Illinois that would be impossible.
In the beginning of the movie Michael is six years old. The rest of the movie is enacted 15 years later, so Michael must be 21 years old. In the end credits however, there's a Michael of age six and a Michael of age 23.
(at around 1h 4 mins) When Lynda and her boyfriend go to the house where Annie is babysitting, they find the house empty. They go upstairs to a bedroom and make love. Afterwards, Lynda lights a cigarette, despite puffing on it, the cigarette doesn't turn red, as it should when you take a puff. Also, when she exhales, you don't see any smoke coming out of her mouth.
Filmed in the spring in California, pumpkins were not in season and the low budget of the movie ruled out creating artificial varieties. Most of the pumpkins and jack-o-lanterns seen are squashes painted orange. As a result they often look somewhat flat or misshapen with the wrong textured skin.
(Extended version) Dr. Loomis and a nurse from the Smith's Grove Sanitarium walk down the hall and discuss who was supposed to be watching Michael Myers when he escaped and the camera pans down to Dr. Loomis' loafers as they enter the destroyed room. In the next scene, walking to his car with Dr. Wynn, Dr. Loomis is clearly wearing brown dress shoes that click as he walk - something the loafers did not do in the previous scene.
(at around 1h 2 mins) After Linda and Bob calls Laurie from the Wallaces' house they go to the upstairs bedroom to make love. There is daylight peering through the blinds behind them, although it is supposed to be night.
(at around 28 mins) Autumn leaves cascade down on Laurie and rustle to the ground as she exits her house in expectation of Annie to pick her up. As she sits at the corner watching children trick-or-treat there are no leaves falling anywhere else in the neighborhood, not even to her immediate right side where the lawn and sidewalk are clean.
(at around 41 mins) When Annie is on the phone with Laurie, the dog Lester comes into the kitchen. We hear him growl, yet by his face he is clearly merely panting. He then begins to bark sharply, yet his tail is wagging and he is clearly looking at the trainer coaching him.
(at around 47 mins) While doing her laundry, the laundry room door blows shut and supposedly 'locks' Annie in. At this point, the lock on the door is in the vertical position. But as soon as Annie tries to 'open' the door, we can clearly see that she turns the lock as she struggles to open it, for when she backs away from the door again, the lock is in the horizontal position, so yes, she 'locked' herself in. When Lindsay comes to fetch her a few minutes later, the lock is mysteriously in the vertical position again.
(at around 1h 16 mins) The date on the tombstone above Annie says that Judith Myers was born November 10, 1947, and died October 31, 1963. That would make her 15 (almost 16) when she died, yet everyone says that she was 17 years old.
When Laurie jabs the needle in Michael's neck, he sticks the butcher knife in the couch. After Michael falls, Laurie picks the knife up, looks at it, and then throws it on the floor next to the couch. Later, Michael comes upstairs holding the knife. Before the end credits, when we hear Michael breathing and it shows all the shots of the house, the knife is still on the floor next to the couch.
(at around 6 mins) After Michael has stabbed Judith, his sister, he leaves the house and when the camera pans upward, all the lights in the house are on. But, they were never on when Michael was inside and he never turned them all on when he was exiting the house.
(at around 55 mins) After Michael has killed Annie, he carries her body around the side of the house. In the first shot, notice her head is to the left side of Michael's body and her feet are on the right side. It then cuts to Tommy who is watching from the window across the street. When it cuts back to Michael carrying Annie up the front steps of the house, her body has switched positions. Her head is now on the right side of Michael and her feet on the left.
(at around 1h 20 mins) When Michael lunges for Laurie with the knife, and she stabs him with the knitting needle, she clearly hits him around the temple, but in the next scene, it is lodged in his neck.
(at around 6 mins) After finding their young son running out of the house holding a bloody knife, Michael Myers' parents simply stand around. They don't try to ask Michael what has happened. They don't try to get in the house to find out if his sister is OK.
After Michael goes upstairs to kill Laurie and the children, Laurie tells the kids to lock themselves in the bathroom in the bedroom, and she herself goes into the closet. Before Michael comes up, she knocked on the door of the bedroom to let the kids know she was okay, so why didn't she lock the bedroom door when she and the kids hid? Michael left them enough time for her to barricade herself and the children in the room, and she could have easily closed the door and locked it.
(at around 1h 6 mins) When Michael stabs Bob with the butcher knife, the knife goes all of the way through Bob and into the wall. However, the knife is barely even long enough to go entirely through Bob's body (if at all), much less the additional length required for it to be deep enough in the wall to hold up his weight.
In the movie's climax between Dr. Loomis and Michael Myers, Michael falls from the balcony of the master bedroom to the backyard below. Laurie had put the kids to sleep here shortly before being pursued. When Laurie was being chased moments before and realized she lost the keys to the Doyle residence, Laurie managed to get Tommy's attention from a bedroom window facing the street in front of the house.