The most famous mess-up is probably the fact that while Dr. Loomis shouts "I shot him six times," he actually shot him seven times during the film's prelude.

When Ben Tramer is hit by the police car, his body falls forward. In the next scene, he is standing straight up. A continuity error.

The police claim the Meyers house is at "45 Lampkin Lane." The address on the front porch clearly displays the number 709.

When Jimmy finds Mrs. Alves on the gurney bleeding all over the floor, he turns to run out the door to get help and slips on the blood and knocks himself out when his head hits the floor. In fact, he's laying right in the middle of the blood!  Later when Laurie is hiding in Jimmy's car, he gets in and the back of his shirt is not a bloody mess at all, it's clean!

When The Shape is drowning the nurse in the scalding water, her towel suddenly goes from being wrapped just below her shoulders to being tied around the waist.

There is a flashing orange light in the back of the marshal's car, but when they turn around to head back to Haddonfield it is nowhere to be seen. It is gone.

Michael Myers back peddles up a ramp when he falls from the balcony in the beginning.

As the ambulance approaches the hospital, notice the hood of the ambulance has red blinking lights. When they stop for the two people (the mother and the childwith the razor blade in his mouth) the blinking lights have moved down to the front bumper.

In HALLOWEEN, Michael Myers falls off the balcony in the backyard. In the beginning of this one, however, the fall takes place in the front yard.

In the scene where the boys ask Mr. Hunt about Ben Tramer, Mr. Hunt says that "it's just a little past 11." Following this up in the next scene Bud lures Karen into the room to kiss her and wish her Happy Halloween. During this scene, as Bud reaches up to kiss Karen, his watch is clearly visible and shows the time as 1:00!

When Michael falls off the balcony at the end of HALLOWEEN, he lands predominantly in an area of the lawn that is more dirt filled. In this film, he lands in a completely grassy lawn.

In the original film, the pumpkin at the Wallace's house was  very small and fat, but in this film (which takes place the same night) you can see when all the cops and reporters are at the house that the pumpkin changed in size and the face got different as well.

On the Goodtimes Home Video box front cover, they spelled Jamie Lee Curtis as Jaime Lee Curtis.  Plus, they use images on the box that are from other HALLOWEEN films, rather than from this film.

In the scene where Marion is calling for help on the police car's 2-way radio, she speaks, "Marion Chambers with Doctor Loomis at the clinic; he's here."  Right after that, the policeman on the other end of the radio starts to talk.  However,  Marion never lets go of the "talk" button on the radios microphone, until the middle of the policeman's response to her request.  You can't listen and receive anything on the radio while the button on the mic is pressed.

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 cemetary.  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 cemetary 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.

In the end credits of the film, it says NIGHT OF THE LIVING DEAD is copyright 1978, when in fact, the movie was made in 1968.

Sheriff Bracket's sideburns don't look the same as in the original film, even though both films are supposed to take place the same night.

If you pause the widescreen version of the movie at exactly 1hr 35min and 34sec (at the end of the film when Laurie is blown off of her feet by the explosion in the Operating Room).  If you examine the right side of the screen you can actually see behind the "set" wall.  You can see the vertical planks that are holding it up and you can see a coiled up cable of some sort hanging there.  Fast forward three seconds to 1hr 25min 37sec you can see behind the wall again, only this time the scene is a little bit darker.  If you watch closely from the moment the explosion goes off and we see Laurie in the corridor, you can see the wall on the right shaking making it obvious that this is a set and not a real corridor.

After the explosion and Michael is walking on fire, you'll notice he is right next to the burning stretcher.  Then they cut to a scene of Laurie hiding behind a water fountain.  In the next scene of Michael, he is now about 8 feet before the stretcher walking towards her again.  He obviously didn't back up.

When Annie's body gets wheeled out of the house and her father closes her eyes, her lids blink even though she should be dead.