There is now way not one teacher or school adult would have NOT noticed Kelly running around the school campus with a stroller! In reality this is child neglect on two counts... one for the baby and another one for EDUCATIONAL NEGLECT for Kelly as she is not able to concentrate on her job as a student.
Zack refers to the school nurse as "Freddy Krueger's mother". In the A Nightmare On Elm Street series Freddy Krueger's mother was a Nun who was raped by inmates in an insane asylum. She was a good, moral character and not a bad, evil character like Freddy Krueger himself, so Zack's comparison does not make sense.