Continuity mistake: A spirit knocks Christine over and gives her a bloody lip. Her boyfriend tends to her lip, which is very swollen. As she sleeps, there is a close up of a fly going into her mouth between her lips that are not swollen at all. After she swallows the fly, she sits up and her bottom lip is swollen again. (00:37:05)
Continuity mistake: During the seance, the white goat disappears for one shot (from high above the table) and then reappears.
Continuity mistake: Petite Christine Brown goes to the cemetery and spends hours digging up the grave of Sylvia Ganush in a pouring rainstorm. In spite of the rain, the 6-foot-deep grave is completely open and the soil is still dry and loose when Christine reaches the bottom. As soon as she reaches the bottom, however, the grave suddenly fills up with over a thousand gallons of water in about 45 seconds.
Continuity mistake: In the scene where Christine is at the women's house at the end of the film, she is sitting at the table with the women and two guys and the goat. The creature is entering the scene and it's very loud. Christine in holding her ears. The next shot, her hands are down and she's looking at the door. In the next shot, she is holding her ears again.
Answer: Because it's a film and Sam Raimi obviously thought it was funny. But I did also wonder.