Continuity mistake: In the first scene when Loomis has just shot Michael. In first film, Loomis looks over the balcony and see that he is gone, but now he goes out and discovers that he is gone.
Continuity mistake: When Michael walks into the old couple's house, NIGHT OF THE LIVING DEAD is showing on the television. At that point, the film is just beginning, with Barbara and Johnny first pulling up to the cemetery. Much later in the film, the security guard is also watching NIGHT OF THE LIVING DEAD on television, and it's the scene where the cemetery zombie is attacking Barbara in her car. This is no more than ten minutes later in NOTLD, yet it's way more than ten minutes later in the evening of HALLOWEEN II.
Revealing mistake: Annie's dead body has a pulse on her neck.
Continuity mistake: At the end of the first film, Dr. Loomis looked down from the balcony to find Michael's body gone. However, in this one, he finds the body missing when looking out of the house's front door.
Factual error: The pagan religious festival Samhain is mispronounced: the correct pronunciation is more like "so-win." This is a character mistake on the part of Dr. Loomis, but as the movie makes him appear quite knowledgeable on the subject and gives it significant dramatic weight, it's arguably appropriate to attribute the error to production as well.
Continuity mistake: When Laurie runs away from Michael Myers in the boiler room, she climbs a window and falls into a storage room. Her hospital gown gets flipped as she falls, exposing her underwear. The close-up shows her falling again, this time without the upskirt shot.
Continuity mistake: Nurse Jill turns around before Michael Myers stabs her. After she's stabbed, she's already facing forward and her head doesn't snap to face the camera.
Continuity mistake: After Nurse Karen is drowned by Michael Myers, he drops her backward. The close-up shows however that she falls forward.
Factual error: At the end when Loomis lights the lighter, the room explodes and is engulfed in flames. Loomis would've burned to death quickly yet shows up in part 4 with burns on his face and arm.
Suggested correction: First, surviving an explosion is unlikely, but not impossible - there are plenty of real-life stories of people surviving fiery blasts. Second, I would argue that it definitely falls firmly under suspension of disbelief, and therefore I don't believe it's a valid mistake. And third, even if it was a valid mistake, this should be a mistake under the "Halloween 4" page, not the "Halloween 2" page.
Audio problem: When Loomis shoots Michael in the opening here his gun sounds different from the previous movie.
Plot hole: Early on, the TV in the Elrods' house is showing a report (corroborated by the authorities) of three bodies being found in the Wallace house. However, later on during the Ben Tramer accident scene, the deputy rushes up to the sheriff to inform him that three bodies were found (including his daughter Annie).
Character mistake: When Ben Tramer's friends report him missing to the police, they describe him as being 17 wearing a mask. This is what leads Loomis to make a positive ID... on Halloween.
Character mistake: The coroner determines that the burnt body of Ben Tramer (still unidentified) must be young, based solely on the absence of fillings in his teeth. Nobody considers for a moment that it could be a 30-something with good dental hygiene.
Continuity mistake: The front door on the Doyles' house is different from the one seen in Halloween. You can see this when Dr. Loomis leaves the house in the beginning of the movie.
Other mistake: After the two doctors and the sheriff pull up in the parking lot and then enter the hospital, Michael suddenly appears to Laurie, and she runs from him across the lot toward the same entrance, and suddenly the doors are locked. There is no way this would be, as the doctors and the sheriff would have had to stop and unlock the entrance before entering themselves, which they did not do.
Suggested correction: The door was already open and then they closed it behind them.
Other mistake: Jimmy the paramedic walks into the major surgery room to find Ms. Alves dead on the stretcher, the blood drained from her body. As he turns to leave he suddenly 'slips' on the pool of blood, falling back first and knocking himself unconscious. However the next shot reveals that the blood pool extends out to the doorway, so there's no way he could have crossed to the stretcher without slipping in the first place while entering the room.
Continuity mistake: After the guy in the hospital slips in the blood puddle he has some blood on his face and mouth that disappear between shots.
Continuity mistake: After Loomis and the police officer see the fake Myers they leave the car with the doors closed but in the open view they are open again.
Continuity mistake: After the hospital guard takes a look outside he checks the trash container which has inside a box with a big bloodstain which disappears in the next shot.
Continuity mistake: When the guard is checking the warehouse at the hospital he holds the flashlight differently between shots.
