Plot hole: Considering the incredibly elaborate plans Maddy makes to have her husband murdered after forging a will she knows is invalid so he dies intestate and she - as his widow - gets his entire fortune, you'd think she would have worked out one little fact - Edmund Walker does not die intestate. It is established in the film that the dud will supposedly written by Ned Racine replaces a previous, valid will which bequeaths half his fortune to his niece Heather. When the new will is declared invalid under Florida law the previous will takes precedence and Heather and Maddy split the fortune. In no way will Maddy get the lot.
Plot hole: In the first scene Alice hears on the radio that three teenagers had been murdered in Haddonfield just down the street from where they live. Yet a few scenes later, the sheriff finds out from his deputy that 3 bodies have been found. Wouldn't the police department know that before it made its way onto the radio news?
Suggested correction: When Alice is on the phone, she tells her friend she can hear the sirens so the police knew about the bodies. As for the sheriff, he'd been busy with Loomis all night. He might have heard about the bodies in the house but figured the other policemen could handle it and that way he could continue helping Loomis. The main reason the deputy came to talk to him, however, was to tell him that his daughter was one of the victims found.
Halloween II was a troubled production, and the scene with Alice was added during re-shoots. Note that the previous scene with Mrs. Elrod also includes a news report about the discovery of the bodies. I've seen no concrete evidence of this, but I've wondered if the scene with Mrs. Elrod was shifted closer to the start of the film, and was originally meant to take place after the scene with the sheriff.
Good theory, but the deputy runs up to the sheriff and informs him for the first time of all three bodies.
Plot hole: When Snake, Brain, Maggie, and the President get to the car at the WTC, Snake opens the hood when the car is dead, and somehow he is out in the open when the Duke is about to shoot. First, how would he get there with a crossbow trained on him, and second, how did Maggie pass the revolver to him, when he hands it to her to open the hood of the car? (01:21:05 - 01:21:50)
Suggested correction: When the hood is opened Maggie can be seen immediately putting the revolver behind her back. Being stood very close to Snake it's assumed it was passed to him offscreen. With the crossbow trained on Snake the Duke monologues directly to Snake allowing him to step a foot or so away from the car to look like he's listening and going to accept his capture but ultimately it was to have a shot at the steam engine and create a distraction. Maggie took out the crossbow guy by slamming the hood on him.