Wrong Address
In "Halloween II", the police say that Myers house address is "45 Lampkin Lane". When you look at the house, the number 709 is clearly visible. Looks like the set department forgot to remove the numbers before filming.
Disappearing Blood
When Jimmy finds Mrs. Alves dead, he turns around to leave the room. He slips, landing directly in the middle of the blood on the floor. He lands on his back. Later when he is seen getting in the car with Laurie, the back of his shirt has no blood on it.
How Many Shots?
In the beginning of Halloween II, a prelude from Halloween I is given. This whole scene was actually reshot for the second film. Dr. Loomis tells the sheriff that he shot Michael Myers 6 times, though when you count the shots fired, there are seven bangs. In the first movie there are only 6 bangs in this scene.
