Willie Wonka was the last movie shown at Jonestown, Guyana, on the day of the mass suicide.
They put this movie on in the main pavillion to keep the Jonestown children occupied while Congressman Ryan and his staff were negotiating for the release of the people who wanted to leave.
You can hear it in the background of the clip referenced in this Reddit thread: https://www.reddit.com/r/Jonestown/comments/18f742g/original_willy_wonka_film_playing_in_jonestown/