When teachers arrive at the college and pass by some buildings, background in the shots that follow don't match the scenery shown in the previous shot with buildings.
When Lucille finds Betty Ann's body, she runs out of the building and while running, falls into mud, dirtying her clothes. In the following shots mud from her clothes is gone.
When killer enters the bathroom at the beginning of the movie, the bathtub curtain isn't in position it was in the shot where woman entered the bathtub.
When the killer reaches through the shower curtain for Cynthia's neck, their fingers don't reach far enough around to strangle her.
Whenever death by choking is shown in the movie, it's too short. It would take longer to choke a person.
La Foret is clearly breathing while dead during inspector's presence in his shack.
When Richard and Miss Clay are leaving the house where he was supposed to meet Lucille, a bush on the left side of the screen obviously moves without being touched by them, probably done by a crew member moving not to end up in the scene.
Dress featured on the poster appears nowhere in the movie.