Factual error: There's no way that the knife that killed Bob was long enough to go through his body and impale the wall behind him. And a butcher knife cannot "pin" a human body to a wall and just stay put, they aren't strong enough.
Factual error: When Dr. Loomis is at the pay phone talking to someone at the mental institution, the background of the scene has mountains, which in fact Illinois has hardly any mountains, and the few it does have are nowhere near there. (00:18:35)
Factual error: It's supposed to be late autumn, but in most scenes the leaves are still very green. [This is because it was shot in California during the summer. Carpenter imported leaves for every shot that you saw leaves blowing on the ground and blew them with a giant fan (this also killed any ambient sound takes); there are also a few shots where you can see palm trees (most prominent the one right in the front yard of Michael Myers' house).]
Factual error: In the scene when Laurie gets stabbed by Michael in the arm she falls over the banister - the camera shows a view of what she sees, falling at that angle Laurie would have broken her neck, spine and hip. But it is still weird how she managed to turn 180 degrees in such a short fall. (01:16:40)
Factual error: There are palm trees visible in several scenes even though it's supposed to be set in Illinois rather than California.
Answer: There are only two families that hire babysitters in the film, the Doyle and Wallace families. Where they went is never explained, but it could be potentially anywhere. They could have gone on a trip out of town for the night, they don't have to be in Haddonfield.
BaconIsMyBFF
Where did it state this was all night? It could have been a few hours. Remember that in the next one, it is still the same night and stays night through the entire movie.