Character mistake: The title card shown after Deborah's suicide states that Michael's escape from the asylum takes place "Fifteen Years Later." Yet the night after the escape, Sheriff Brackett refers to her suicide having been seventeen years ago. (00:38:40 - 01:29:00)
Continuity mistake: Laurie drops the items in the mail slot twice at the Myers' house. (00:58:30)
Factual error: When Laurie, Annie, and Lynda are walking home from school on Oct 31st, you see the "fall" leaves on the ground, however the surrounding trees are as green as can be. (01:04:15 - 01:05:30)
Character mistake: When Sheriff Brackett is talking to Loomis at the food stand, he calls him Don. His name is Sam. Even says it in the subtitles. (01:19:35)
Suggested correction: He could possibly be saying "Doc".
No, he's definitely saying "Don." It's never been addressed, but I think it's an honest mistake with two people who have never met before and maybe an homage to Donald Pleasance, who played Loomis before.
It's hard to say, but it does sound like "Don." The sheriff says "doc" two times later in the same scene and those two times definitely sounds different than the first time. But I don't think it's meant to be a homage to anyone. I think it's just an actor who flubbed the word.
Plot hole: Laurie calls the police from 1987 Winchester drive, and gives them that address. Yet the police responding to the call go directly to 1960 Winchester drive - where Laurie has run to and is now hiding - even though it's on the other side of the street and several houses down. (01:31:30 - 01:33:40)
Suggested correction: Initially Laurie sends Lindsay across the street, back to the Doyle house to call the police. It's possible Lindsay gave the police the Doyle's address (since that's where she was calling from). Since that call was likely made before Laurie made her call, that explains why the police first show up to the Doyle's house (responding to Lindsay's call) and Bracket shows up minutes later at the Wallace's house (responding to Laurie's call).
Other mistake: In the original ending, after Laurie is pulled out of the cop car, Loomis is able to reason with Michael to let her go. After he does, he is shot to death by the police. This was obviously changed, but when Loomis is reasoning with him in the final cut, you can still see the police standing behind him. (01:46:00)
Suggested correction: The police came anyways. He is a wanted killer, after all.
During the timestamp above, an officer standing behind Loomis with their gun ready while he's talking to Michael, but besides these shots, the officer is nowhere to be found. In the alternate ending, this confrontation is completely different as cops are shown actually pulling up behind Loomis. You are able to see that shots from the alt ending are used in the final movie, thus making the mistake valid.
Continuity mistake: Michael runs at Laurie and they both land on the ground. All the way down, Michael is on top of Laurie. Next shot shows Laurie on top of Michael. (01:53:45)
Factual error: Federal institutions have strict rules for inmates or patients based on the reason for their incarceration, including substituting metal utensils with safer plastic ones. Despite being convicted of brutally killing his family, Myers is still trusted with a sharp metal fork - resulting in the nurse's death.
Revealing mistake: In the beginning of the movie, when Michael removes the knife from the drawer, you can see the blade bend.
Continuity mistake: When Laurie's mom is struggling to get to the phone after Michael stabs her, she reaches for it, knocking it off the hook. When Sheriff Brackett calls later on, the answering machine picks up.
Continuity mistake: In the beginning, after Michael kills his sisters boyfriend, he puts the mask on with bloody hands yet he gets no blood on the mask.
Continuity mistake: When Laurie stops at the Myers house she has no backpack. She does in the next scene.
Continuity mistake: Laurie's hair changes from curly to straight frequently in the Myers' house.
Continuity mistake: When Michael Myers busts into the bathroom stall occupied by the truck driver, the glass on the framed advertisements on the opposite side of the stall is broken and we hear glass hitting the floor. When Myers leaves the stall, the glass in the frame is still intact.
Continuity mistake: Near the film's end, Myers crushes Dr. Loomis' skull with blood protruding from several parts of his face. In the following shot of him being dragged into the house dead, his face and head are perfectly fine.
Factual error: There's no way a body can be pinned to the wall with the tip of a butcher's knife.
Continuity mistake: When Grizzly the truck driver stops at the truck stop, the attendant opens the hood and gets the hose twice.
Revealing mistake: In the rape scene, the guard hits Michael in the back with a baton. It leaves an indent in the material of the suit he's wearing underneath his robe.
Revealing mistake: When Michael is young, at Christmas, Dr. Loomis approaches Smiths Grove. There is snow on the ground, but the leaves on trees are green.
Continuity mistake: When Michael beats the kid in a park with a stick, the attack only lasts a minute yet the new blood on the kids face is dried up, presumably from earlier takes. The dry blood effect is seen in more scenes throughout the movie.
