The airport. Seems as good a place as any to wrap up a movie, wouldn't you say?
There fog and the tension are thick enough to cut with a knife.
Rick tells the airport orderly to put Victor and Ilsa's baggage on the plane, and here's where he has to break it to Ilsa that he isn't getting on the plane with her—Victor is.
She takes some persuading, but Rick finally convinces her that he's decided this is all for the best, and he's finally willing to put his own feelings on the back-burner in favor of the greater good—she belongs with Victor.
Rick then proceeds to casually rattle off, oh, three or four of the most famous lines in movie history as if it were nothing.
Victor, Ilsa and Rick say their good-byes, and Rick hurries them onto their plane. It heads down the runway just as Strasser pulls up.
Strasser tries to call the radio tower to have them stop the plane, but Rick (after giving him a polite warning, mind you), shoots him in the chest. And the crowd goes wild.
A car full of gendarmes arrives, and Renault informs them that Strasser has been shot. He tells them to "round up the usual suspects," refusing to give up Rick.
As the plane takes off, Renault tells Rick it would be wise for him to leave Casablanca for a while.
He then implies that maybe the two of them should vanish together, especially seeing as how he's just done a little justice-obstructing himself.
In the last scene, there's the iconic image of Rick and Louie walking off through the fog, and Rick saying "this could be the start of a beautiful friendship."