These are the other four interplays in my top five from that movie:
Captain Renault: What in heaven's name brought you to Casablanca?
Rick: My health. I came to Casablanca for the waters.
Captain Renault: The waters? What waters? We're in the desert.
Rick: I was misinformed.
Annina: Monsieur Rick, what kind of a man is Captain Renault?
Rick: Oh, he's just like any other man, only more so.
Yvonne: Where were you last night?
Rick: That's so long ago, I don't remember.
Yvonne: Will I see you tonight?
Rick: I never make plans that far ahead.
Major Strasser: What is your nationality?
Rick: I'm a drunkard.
Captain Renault: That makes Rick a citizen of the world.