I’ve often wondered about Help and Hard Days Night.
The girls chasing the Boys down streets looks real. And the running around on the airfield thing looks like it might have been without permission(or actual Direction really).
Unrelated trivia: one of those boys was a young Phil Collins.
Much of Kevin Smith’s Clerks was shot guerrilla style. Smith worked at the convenience store in real life, and had the owner’s permission to shoot inside the store after hours. The material shot elsewhere was generally without permits.
Jafar Panahi, director of Oscar-nominated It Was Just an Accident is well-known for his guerilla filmmaking ever since he was banned from filmmaking by the Iranian government.