I got my hands on the film SLC Punk! (1998) around the time I was trying to watch every movie with James Duval in the credits. I never watched it because, well, it looks kinda sucky. I can confirm that it’s mostly just blurry-camera acid trip scenes and lots of talking to the camera.
But towards the end Jason Segal’s character (the apparently mild-mannered but outrageously violent “Mike”) announces that he’s moving away to get an education and save the environment, thereby becoming (as far as I’m concerned) How I Met Your Mother’s green-minded lawyer, Marshal.
This is one of my favourite things - when an actor plays two completely different characters at two completely different stages of their careers, but you can kind of fudge one into being the backstory for another. Like how Kal Penn decides to go to medical school at the end of Harold & Kumar Escape from Guantanamo Bay (2008), and then turns up as a doctor in the TV Series House, (Robert Sean Leonard does the same thing if you ignore the last 20 minutes of Dead Poets Society).