Plot hole: Mrs. Tingle was tied to bed for longer time, fed by her students, but what about going to toilet within this period?
Visible crew/equipment: At the very end of the movie, during the best student award, while the graduates are applauding you can see a sound engineer with a microphone pole on the right side. (01:28:15)
Other mistake: Sometimes in some scenes, you can see Mrs. Tingle's bra before they even open her pyjama jacket. For example, when Luke is feeding her the hamburger.
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.
Other mistake: In the scene where Mrs. Tingle is on the loose and threatens Leigh Ann with the bow and arrow, she is really scared. But when Jo Lynn takes the bow away from Mrs. Tingle and threatens to shoot her, Mrs. Tingle shows her that she can't shoot her because the arrow is on the desk. Why would Leigh Ann be afraid of Mrs. Tingle then, if the arrow was on the desk? (01:22:00)
Suggested correction: The arrow was in the crossbow. Ms. Tingle slipped it out when the bow was taken from her.
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)