Rorschach: You forgot how we do things, Daniel. You've gotten too soft. Too trusting. Especially with women.
Dan Dreiberg: No, listen, I am through with that! God, who do you think you are, Rorschach? You live off people by insulting them and nobody complains because they think you're a damn lunatic! I'm sorry. I shouldn't have said that, man.
Rorschach: Daniel? You are a good friend.
During the final confrontation in Veidt's lair, you see the actor Billy Crudup in his SFX suit reflected in Nite Owl's goggles, not the image of Dr. Manhattan.
During the opening fight scene, Comedian throws a mug at his attacker, but misses. The mug strikes the numerals on his apartment door, knocking the '1' off. This turns 3001 into "300", the name of the director's previous hit film.