In the Week 1 module, Richard notes that film scholar Don Crafton describes gags of early slapstick serving "as as a source of narrative 'excess'". In other words, gags tend to be breaks from the plot and traditionally storytelling, intending to be used just for exaggerated humor.
What I'm wondering is if there have been gags, either in early slapstick or present-day, where they were crucial and pivotal to the progression of narrative--where the plot simply wouldn't drive forward without the execution of said gags?
Buster Keaton--perhaps?--whose gags tend to be forces of nature outside his control, and which very often sets off the circumstances of the rest of his films.