Continuity mistake: During the trial when Beverly is cross-examining Mrs. Ackerman, her neighbor, she asks if those were her scissors found sticking out of Mrs. Sterner's stomach. That's not where the scissors should have been found. After stabbing Mrs. Sterner with the scissors, Beverly pulled them out and threw them at the husband twice, both times they ended up sticking in the walls, and that is where the scissors would have been found when the police arrived.
Continuity mistake: During the opening, when the fly finally lands on a coaster, Beverly Sutphin swats it quickly and removes the swatter. Cut to a close-up, and the swatter and dead fly are still there.