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: I have read that, in early drafts of the script, the hospital was a health clinic, not a standard hospital. This would possibly explain why there are only a small number of patients, though it doesn't explain why there is a maternity ward, or why the mother brings her son there for emergency treatment.