It was from the episode "Patriot Act" which I thought was one of the best JLU episodes.
What caught my eye (ear actually) was the little exchange between Green Arrow and Speedy at the beginning....
Green Arrow: The Crimson Avenger and my ex-sidekick!
Green Arrow: Speedy...we gotta do this now?
What made this funny (and cool) to me was that four years later in Young Justice, Speedy would be the main catalyst in the separation of the heroes and their "sidekicks".
He was even the one that delivered the line "Don't call us sidekicks".
Even though, I know JLU and Young Justice are set in different universes, that kind of tip of the hat is what makes the DCU cool to me.