When Serial Mom is in the beige van chasing Scotty in the red LeMans, the LeMans' hood is ajar during one shot in the middle of the chase, and shut the rest of the chase.
In the first Sutphin family dinner scene, Beverly (Kathleen Turner) serves Misty (Ricki Lake) a piece of meatloaf. In a medium shot of Beverly, the piece of meatloaf is clearly the end or "heel" of the loaf, dark and rounded on one side. In the next shot, a medium shot of Misty, the piece of meatloaf is from the middle of the loaf, a lighter shade, large, and not rounded on one side.
In the main-title sequence, when Beverly swats a fly on a tray on the Sutphins' kitchen table, she brings back the swatter to an upright position as quickly as she swats the fly. However, in closeup in the next shot, the swatter is down flat on the tray. Once established, the swatter is pulled away more slowly than in the preceding shot, revealing the squashed fly. After the squashed fly is revealed, the director's credit appears.
When Mrs. Sutphin arrives at her son's school to meet his teacher, the time is given as 3:36 pm. Very soon after, she takes her seat in the hall and is invited almost immediately into the classroom, where the clock reads 4:10 pm.
During the first dinner scene, it is shown to be brightly lit and sunny outside. Seconds later Rosemary is running to the house, and the time of day appears to be after sunset, with the house and garage lights already on. Once Rosemary enters the house, it again appears to be bright and sunny outside.
Beverly would never come out of the courthouse innocent. Early in the movie, fingerprints were found in the murder weapons that she used, most notably the fire poker and scissors.
When Mrs. Jenson is watching Annie at her house and singing "Tomorrow" and Beverly breaks into her house to kill her. Tomorrow keeps repeating when the opening credits should be done and the movie should actually start.
When Beverly goes to Chip's school for a P.T.A. meeting, Mr. Stubbins says Chip is "off to a fine start this year". However, a card in the opening scene established that the day is Friday, May 14, 1993, which would be nearing the end a school year, not the beginning.