I added this link as a response in another forum, but I think it contains enough knowledge and lore to stand on its own. Back in the day, Keystone studios was notirious for pie-throwing films, to the point that it was nearly all that it was doing. (This article contains some interesting how-tos on making a throwable pie, too

https://www.atlasobscura.com/articles/why-do-people-throw-pies