Julie Walters joking on the set after having her character(Molly Weasley) defeat Bellatrix Lestrange.
The sparking glove effect seen throughout the movie was achieved by attaching the glove to a car battery. The famous scraping noise was created by scratching a steak knife on the underside of a metal chair.
A Nightmare on Elm Street (1984)
Although the film was an initial failure, the arcade video games based on it proved to be a tremendous hit and actually out-grossed the film.Tron (1982)