Just after Marjorie attacks Joe, she splashes boiling water in his face from a whistling tea kettle on the stove. When she and Joe were just in the kitchen two scenes before, she never filled the kettle or put in on a burner. It sat to the side, empty.
When Marjorie (Farrah Fawcett) makes her rush for the bathroom and locks herself in, her face is a mess, she has been crying and her face is soaking wet and make-up streaked, but as soon as she locks the bathroom doors and turns around, her face is dry with clean make-up.
When Marjorie (Farrah Fawcett) first puts Joe (James Russo) in the fireplace, his eyes are fresh from being sprayed with bug spray and are swollen shut so he can't see, but once in the fireplace he opens them wide open and looks directly at Marjorie as though he can see her clearly.
About 20 min into the film when Marjorie (Farrah Fawcett) is digging in the garden she is wearing loafers on her feet but in the next scene she is wearing thongs (flip-flops)
When Terry was going to the pharmacy for the atropine, they said it was 5:35. Marjorie then told her to be back by 5 or she would kill Joe.