Anachronisms: Mentions of AstroTurf (introduced in 1965) in 1963.
Factual errors: Although the latter portion of film takes place in January, we never see any evidence of snow, even though the film is set in Massachusetts. Also, the characters don't always seem to dress appropriately for winter in Massachusetts, dressing more as if it were autumn.
Continuity: Charlotte's blue eye shadow disappears and reappears as she goes to/returns from the hospital.
Continuity: During the fight between Charlotte and Mrs. Flax (in the kitchen, after Kate nearly drowns,) Mrs. Flax leaves the kitchen and returns with a suitcase, the mascara of her right eye running down her cheek. We cut away, and quickly cut back; her eye makeup is perfect.
Anachronisms: As the groceries are being put away, a Dole can with a 1990s logo is visible in the refrigerator.