I always pictured them being captured in Lisbon by the gestapo. With the help of Ferrari’s connections Rick, Sam and Renault have to rescue them from a train bringing them across occupied France headed to Germany and get them back to Casablanca. It’s the romantic in me?
I do think the way Casablanca ended was perfect with the two walking off together. Just didn’t like the way he left it with Sam.
Wait... how did Rick leave things with Sam? I remember him selling his club to Ferrari and telling him his one condition is that he keep Sam on, and Ferrari was all, "of course, he's the best musician in town."