It's been a while since I've seen one of his movies, and I'm not entirely sure if this is long enough to count as a riff, but there's the famous debate in Clerks about the moral problems involved with blowing up the Death Star in Return of the Jedi because there were innocent, non-combatant union space workers on it. It was one of those quintessential "geek" conversations, drilling down into the minutiae of a movie that no one but a true geek would think or care about.