I was just watching Casablanca. A great movie, but you already knew that.
One thing struck me. Plenty have noted how silly the "letters of transit" are, much less ones that can't even be questioned. Come on, if the Nazis wanted to stop Paul Henreid, would they really let a document stop them?
But another thing hit me. Ugarte (Peter Lorre) has had the letters of transit for a while. Then, for some reason, he asks Rick (Humphrey Bogart) to hold them. It's a necessary plot point, but why does Ugarte bother? It's not like he's worried he's being watched, since he has no plan when he's arrested soon after except to run away. Besides, he's going to make the transaction in only an hour or so when he gives the letters to Bogie.
PS Boy does Dooley Wilson do some of the worst fake piano playing I've ever seen.