Continuity mistake: When Mrs. Tingle is holding the diary in the classroom, you can see that her nails are short, but later in the movie when her right hand is untied by Jo Lynn, she has long nails.
Continuity mistake: Just before Mrs. Tingle shoots the arrow and accidentally hits Trudy, Leigh Ann is near the door trying to escape. She opens the lock, disappears and then the arrow hits Trudy. She couldn't have escaped without running into Trudy. (01:24:50)