R violence type: blood, gore and graphic.
Some scenes are pretty gory and strong, but overall the violence is usually not particularly graphic. The aim of Detention's violence is to shock but also to amuse, so many of the gory scenes have a humorous undertone.
At the beginning Taylor vomits into a toilet on purpose. Nothing is shown.
Clapton vomits into a urinal it is shown from a distance, and then it is zoomed into displaying the name of a credit at the beginning
A serial killer armed with an axe murders several teenagers throughout the movie: most of them get stabbed to death; a guy has his arm cut off and then gets his throat sliced (lots of blood); a girl is decapitated with an axe (graphic). A girl is stalked by the killer who is trying to kill her but does not succeed. There is a rather high body count.
The films-within-the-film are gory, and feature one torture sequence and several stabbings. A girl is forced to place an item inside her stomach, so her insides are visible.
A character blows himself up. Blood splatters everywhere.
A girl attempts suicide by hanging herself, but it is treated in a joking manner.
A girl gets her throat slit. She is stabbed repeatedly, then thrown out her bedroom window and finally lands on a car. Lots of blood sprays.
A dog explodes. The scene is very brief but also very gory.