Annie's death, especially Sheriff Brackett's reaction to it. The man had his daughter survive being attacked by Michael, only for Michael to kill her two years later, even though he set security patrol in front of the house...he tried to make sure she was safe and failed. Then Laurie, another surviving victim he had taken in like a second daughter, is either insane or dead by the end depending on the version of the film.
Lynda's dad confronting Dr. Loomis at his book signing. It can be very upsetting to see someone cashing in on not only the deaths of many other people in the last film, but the death of your own daughter.
It's pretty hard not to feel sorry for the woman who apologized to Michael after her father and another redneck beat him up, given that Michael still killed her.
