Our school requires permission from the Principal as the first step and then if PG-13 or higher, parent permission is required. Our Principal won't sign off on the permission slip unless the movie is educational (except at holiday time in December and at end of the year in May... two weeks of fun!).

VCR's aren't just kept in the classrooms... you have to show the librarian your permission slip from the Principal and then you can roll the VCR to your room

I'm speaking as a sub teacher as well.

As far as the OP's situation, I'd certainly let the Principal know what happened and let him/her take care of it. The school might need a more strict policy on how movie watching is handled...