Character mistake: The police claim the Myers house is at "45 Lampkin Lane." The address on the front porch clearly displays the number 709.
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.
Answer: There is a scene where Laurie dreams about meeting Michael as a young teen. It's unknown whether this is an actual memory of real events, but since nothing indicates otherwise, we could assume the he saw her at an older age when she looked closer to her 17-year-old self.