Corrected entry: Surely the presence of a dead body in the water supply would contaminate the water?
Corrected entry: At the very end of the movie when Ceci and her father are driving away, you see them ignore a stop sign that is painted on the road and not stop.
Correction: Character mistake, not movie mistake. Real people do this ALL the time.
Correction: Probably, but who's to say the water wasn't contaminated? The news is full of stories of contaminated water, polluted water, toxic dumps and landfills, etc. Just because it was not specifically mentioned in the movie doesn't mean it was not contaminated. People often drink contaminated water, or live in other unhealthy conditions without knowing it, and health problems may not occur for years.