When Sara and Therese are chased through the house and crash in to the drain pipe, Therese's top changes from red to blue and back again.
In the opening a girl jumps to her death from a tall building. When she crashes in the hard ground her body should burst, which does not happen. In real life there would be some bleeding.
It's very unlikely that the locker of a student who committed suicide would still be filled with her belongings the year after her death. Why did the police not confiscate her belongings in the following investigation or did the school empty her locker?