Pretty interesting list...

Time Code (2000)
Rule Breaking Idea: Show four frames simultaneously on the screen

 

Star Wars: Episode V - The Empire Strikes Back (1980)
Rule Breaking Idea: The good guys lose

 

Russian Ark (2002)
Rule Breaking Idea: Instead of making a film with 20-30 scenes, make a film with one 90-minute scene, shot in a continuous take.

 

Requiem for a Dream (2000)
Rule Breaking Idea: Make a truly anti-drug film
...

 

http://glipress.blogspot.com/2008/05/review-13-rule-breaking-films.html?pagewanted=all 

Star Wars was the first movie to not have opening credits, right?

That was a rule breaker.