Re: Fatal Flaw?
Jim, considering you teach this, I'm probably not going to convince you of anything, but I'll give it a shot.
Rick is the active character making choices. He begins the movie denying he loves Ilsa, and denying he cares about which side wins the war. His actions during the movie show that both of those statements are untrue.
He's the one at the end with the impossible choice: does he get on the plane with Ilsa, and let a leader of the resistance get captured? Does he send Laszlo away and stay with Ilsa, even though that wouldn't be safe for her? Does he protect the two things he loves - Ilsa and the resistance - by sending them both away, even though he's sacrificing his own happiness?
If you're correct and the protagonist of the movie is Laszlo, then he's pretty much the least compelling protagonist in the history of cinema. If your protagonist spends the end of the movie standing there with his dick in his hand while someone else decides his fate and does everything for him... you've got a problem.
And on top of all of that, it was an adaptation (of a play).