In the original movie, the Myers house was a small Victorian home; in this film, it is a Gothic mansion.
At the beginning of the film, we see Jamie realize that Michael Myers is alive. She grabs her chalkboard & writes "He's coming back." on it. Yet a few scenes later, Loomis is demanding that she write what she knows about Michael Myers. Yet the chalkboard & its message are never seen again.
(at around 1h 23 mins) When Jamie climbs into the laundry chute, her right shoe falls off then reappears on her foot.
(at around 58 mins) Samantha removes her gloves twice when she is with Spitz.
(at around 1h 19 mins) A bullet hole appears in the door before Charlie starts shooting.
(at around 1h 19 mins) When Charlie (the cop) and Jamie are climbing out of the 2nd floor window, Charlie fires ten shots from a revolver.
At the end of the film, Michael Myers is shown shackled in a police jail cell, yet he is allowed to continue to wear his mask.
After Michael has fallen into the mineshaft at the cemetery, an officer lights a stick of dynamite and drops it in there after him. In reality, no law enforcement officer would use dynamite to dispose of a suspect because that would be ruled as excessive force.
As with the previous film, Sheriff Meeker and his men are shown working at the Haddonfield Police Department rather than the (Warren) County Sheriff's Department, which are two separate law enforcement agencies. The station itself, patrol cars and uniforms all incorrectly refer to "police" rather than sheriff. While in reality the town could have both, it is clearly established in the film (and those before it) that Meeker is in sole charge and thus there should only be a sheriff's department.
Toward the end of the film, Michael is left shackled inside a jail cell. As long as the door is secured, there would be no reason to leave him in shackles.
Although it is supposed to be Halloween it is obvious that it was filmed in the spring/summer because all the trees are in full bloom.
(at around 4 mins) The opening scene, in which Michael escapes the mine shaft, takes place immediately after the conclusion of the previous movie, Halloween 4: The Return of Michael Myers (1988). However, Michael isn't wearing the 'Halloween 4' mask; he's wearing the 'Halloween 5' mask that is seen throughout the rest of the film.
(at around 4 mins) A safety line can be seen attached to Michael's jumpsuit when he grabs onto the netting in the river.
(at around 43 mins) When Michael is driving with Tina in the car and wants a pack of cigarettes, he slams on the brakes and backs up, revealing there are no back or brake lights on the car.
Before placing Michael into a holding cell the Haddonfield police would first take his picture and prints to make sure the correct prisoner is released when he is turned over to the National Guard for transportation to a maximum facility. Yet Michael still has his mask on which should have been put into evidence after taking his photo.
(at around 42 mins) When Tina is saying to Michael, "Nothing Mike, that's what I get, nothing," her lips are out of sync with what she is saying.
(at around 1h 6 mins) Tina yells "Jamie!" when Michael crashes into the tree, but her mouth is closed.
(at around 32 mins) When the Man in Black walks around, spurs can be heard jingling, but he's not wearing any.
(at around 1h 3 mins) When Michael is chasing Jamie and Billy in the car, Tina yells "Jamie!", but we hear "Billy!" come out of her mouth.
(at around 1h) In the barn, Samantha yells, "Son of a bitch!" to Michael with her mouth closed.
(at around 35 mins) When Mike is parking his car outside the store where Spitz works, we can see lighting equipment hanging over the car reflected in its shiny surface.
(at around 35 mins) Cameraman visible in the car mirror as Mikey is waxing his car.
(at around 1h 4 mins) When Michael is chasing Jamie Tina and Billy in the car before he crashes into the tree you can see the camera in the back seat of the car.
In the beginning when the clinic is showed during the day for the first time you will see a tall camera light to the right.
When Myers is floating down the river in the beginning, the protrusion of a life jacket can be seen under his suit.
We see the police, along with Jamie and Dr. Loomis, set up a stakeout at Michael Myers' house. But a few scenes later, we see that Michael Myers has an attic full of dead bodies. Why didn't the police find these when they searched the attic before the stakeout?
We hear Tina whisper to her boyfriend Mike to pick her up at 8PM, at Rachel's house. A disguised Michael Myers appears at that time instead, but he had no way of knowing when or where to show up.
There is a scene where Michael chases Jamie and Billy in a car. People tend to learn how to drive while in high school, but Michael spent those years in a mental institution. So, he could not have known how to drive.
(at around 13 mins) When Loomis and Rachel are standing outside the hospital after the brick was thrown through the window, the boom is reflected in the window beside Loomis.
Every character in this film refers to Darlene Carruthers as Jamie's "stepmother", when she is actually her foster mother, as established in the previous film.
(at around 6 mins) Jamie has a flashback to killing her mother in Halloween 4: The Return of Michael Myers (1988). Her mother only screams once in the fourth movie, but screams multiple times in this flashback.
(at around 21 mins) When Loomis and Meeker are talking down at the station, Loomis recalls the events of the first movie saying "my memory goes back 12 years." Since Halloween 5 is set in 1989 and the events of the first movie were in 1978, he should have said "11 years."
(at around 44 mins) When the cop at the pageant radios Meeker, he refers to him as "Sergeant Meeker", when in fact Meeker is the sheriff.