(at around 2 mins) In Halloween (1978), Michael falls off the back balcony of the Doyle house, however in this film he falls off the front balcony. The balcony in the first movie is a covered balcony, the balcony in this film is not.
At the end of Halloween (1978) Michael Myers was shot by Dr. Loomis six times, and in this movie it's said repeatedly that he was shot six times. In the recreation of that scene at the beginning, however, it's seven. Additionally, seven shots would not have been possible from Loomis' six-shooter.
Jimmy passes out lying in a pool of blood, but later in the car there is no blood on him anywhere.
[TV version] The security guard is sent to find the reason the phones do not work in the hospital. A couple of scenes later, you see a nurse chatting on a hospital phone.
(at around 41 mins) When Officer Hunt calls for backup at the Myers' House he says that the address is "45 Lampkin Lane." The address on the house is 709.
(at around 1h 12 mins) When Michael corners Laurie in the elevator, the door slams on his hand and keeps closing. Elevators have rubber guards that cause the door to open again if someone's hand would get caught in the closing.
The elevator should've never taken Laurie from the basement to the first floor because she didn't make a selection upon entering- all of the elevator buttons are unilluminated as she cowers in the back from Michael and the closing doors. In reality, the elevator car would've stayed dormant on the basement level.
Nurse Jill's name tag has 'R.N.' after her name, which stands for 'Registered Nurse'. Registered Nurses have black stripes on the cap, like Nurse Mrs. Alves. Nurse Jill's cap does not have the black stripes, indicating she is in fact an L.P.N., or Licensed Practice Nurse, not a Registered Nurse.
(at around 52 mins) Water at 125 degrees Fahrenheit is not hot enough to scald a body. Minimal effects usually start at about 140 degrees.
Despite taking place in the same night, the decals on Sheriff Brackett's car have noticeably changed since the previous film.
At the beginning of the movie, it is mentioned several times (on TV on the radio and in telephone conversation) that 3 teenagers were killed, but then police discovers the bodies only after that - which the audience learns in the conversation between Sheriff Brackett and his deputy who tells him they have just discovered 3 bodies "in the house across the Doyle's house", and that his daughter was one of them. However, the audience is never shown the exact sequence of events. Law enforcement could've discovered the bodies well before Hunt informs Brackett about Annie. The deputies likely wouldn't have wanted to tell Brackett about his daughter's death over the radio, and it likely took a little while to catch up to have as he was roaming the streets with Dr. Loomis.
(at around 1h 15 mins) When Loomis and the nurse are in the deputy's car, Loomis shoots out the window and the car makes a hasty reverse turn. On the road, there are at least 2 identical swerve marks. This would indicate the scene had been shot multiple times.
(at around 31 mins) When Michael is hiding in the nursery, it is obvious that the "baby" closest to the camera is a doll.
The actor that portrays Laurie Strode's father is listed in the closing credits, but he never appears in the movie.
The film takes place in Illinois on Halloween, but you'd never know it looking at the colors of the trees, they are all a healthy green.
Haddonfield is portrayed as a small Illinois town in the film- when taken to and admitted in the hospital Jimmy, Dr. Mixter, and Nurse Jill called Laurie personally by name. Bud also figured out that her father ("her old man") owned the realty business. However, it took Sheriff Brackett's peers an hour to inform him that his daughter Annie was one of the victims at the Wallace residence.
During an overnight shift the lights in the hallway of the hospital ward are almost always on. In the event someone needs to get to a patient's room quickly they won't have to switch the lights on first.
When the Sheriff sees his dead daughter, Annie, he closes her open eyes. Before the blanket is put back over her, you can see her eyes move.
The film takes place in 1978, but the ambulance has rectangular headlights, which were not introduced on full-size Ford vans until the 1980 model year.
Set in 1978, some of the clothing and hairstyles have noticeable characteristics associated with the early 1980s; particularly those of Alice, Karen, and Darcy.
(at around 9 mins) The Elrods are watching Night of the Living Dead (1968) and we hear Johnny's dialogue, "They're coming to get you, Barbra" overlapped by the movie's music score. In the actual movie, the music score doesn't begin until after Johnny is attacked and Barbra begins fleeing.
When Jimmy is telling Laurie about who attacked her that night and he says "It's on right now" (referring to the media coverage), the shot from behind shows that his mouth isn't moving and he is sitting very still with his hand on her waist.
(at around 1h 17 mins) The car horn keeps blowing for a split second after Laurie pulls Jimmy's head off the button.
When Laurie is being wheeled away in an ambulance, the camera's shadow can be momentarily seen on her and the house's shrubbery; the same thing happens when she's being wheeled into the hospital.
(at around 1h 25 mins) On the widescreen DVD, when the hospital room blows up, you can see around the set wall twice for about a second each time.
The reflection of the blue gel spotlights can be seen in the windowpanes of the Doyle residence when Dr. Loomis exits the front door after shooting Michael.
The cameraman's shadow can be seen on Loomis, before he leaves Haddonfield.
On high definition modern releases of the film, when Michael falls from the balcony in the opening scene, the shot is framed too wide and you can see him land on the stunt mat and not the front lawn.
Other than a patient that Jill responds to, no other patients are ever seen or heard throughout the large hospital, despite the fact that the maternity ward has several newborn babies.
Considering how immense Haddonfield Memorial Hospital is (it has wings), and the fact that it has an emergency room and surgical ward, it should not have just four nurses, one doctor, and two ambulance drivers staffed for the entire hospital, even if it is the night shift.
Not only does Loomis not know about Laurie's relationship to Michael Myers, he also doesn't even seem to know a younger sister existed. Marion has to explain the background to him, which she got from a file that would have been sealed "after the parents death" - a full two years after Loomis was already Michael's doctor. So even though there was a sealed file, the information it contained was not secret for a full two years before this happened, and Michael's doctor would have been very familiar with a fact as obvious as the patient's basic family unit. Even if he did not know who adopted Laurie, the fact that she existed would not need to be explained to him.
When Ben Tramer's friends are reporting him missing to the police, the only details they give are that he's seventeen and 'wearing this stupid mask' (on Halloween, mind you.) This unbelievably vague info is all Loomis needs to crack the case of the burned body in the morgue.
Nurse Marion says that Michael's parents were killed and then says they died in the same speech.
(at around 53 mins) Dr. Loomis and the policemen find the word "Samhain" written in blood on a wall in the elementary school, and Loomis first pronounces the word literally, before saying it is "the lord of the dead." Both of these things are incorrect. Samhain is a Gaelic word pronounced "sah-win," with a stress on the first syllable, and it was a festival marking the end of the harvesting season and the beginning of the "darker half" of the year.
(at around 40 mins) Dr. Loomis says that Michael is 21 years-old, yet when the credits appear at the end his age is given as 23. (This was a mistake in the credits for the original Halloween (1978) film. As Michael was 6 years old when he killed his sister Judith, in 1963, he would have been 21 15 years later in 1978.)
Multiple times throughout the movie, Dr. Loomis says that he fired 6 shots at Michael Myers. However, 7 shots are clearly heard at the beginning of the movie when he shoots Michael.
In the ambulance, Jimmy tells Laurie they're taking her to "the clinic." The radio announcer also reveals that Laurie was taken "across town to Haddonfield Memorial Clinic." However, the jackets that the medics wear, as well as all the signs at the hospital, indicate that it's actually Haddonfield Memorial Hospital.
When Nurse Jill is talking to Jimmy, he tells her to go check the east wing again and then drive to the Sheriff's office. In reality, Jimmy should be the one to leave the hospital if necessary because a nurse is more valuable to have on hand in the event a patient needs medical attention.