The toy Niki grabbed from Akemi's backpack is shown being destroyed in one scene, but a day and several scenes later, the toy is shown again completely undamaged.
In the scene where the girls are tormenting Niki, the topless red haired girl's underwear disappears in one shot but reappears in the next.
The blonde girl having sex with Niki is shown wearing dark stockings. As the scene meets an awkward turn however, the blonde's legs are bare and then her stockings reappear in the next shot.
The girls tormenting Niki were apparently hiding out in the school's gym equipment room, as in on school grounds. All seven of the girls are horribly mutilated in that very room, but the next day school is still open and the students make no reference to the event.