Other mistake: After the Sanderson sisters are done sucking the life out of Emily Binx, they do a little dance thing after they become younger. When either Winifred or Mary swings past her, Emily's leg moves even though she's supposed to be dead. She's also playing with her hands and bobbing her head.
Other mistake: When Sara lures Emily to the Sanderson house with her song, Emily is laughing and running even as she enters the house. Later in the movie when Sara lures the town's children to the Sanderson house with her song, they were all in a hypnotic sleepwalking state.