It sure would have been rough if Humphrey Bogart had died during filming. Well the producers thought so too, which is why they took out a $100,000 insurance policy in case he died before shooting was completed. It must be tough to be told you're only worth $100,000 when you look like a million bucks. (Source.)

They didn't actually use a full-sized plane in the airport scene. To maintain proper perspective, little people were cast as the crew members. (Source.)

The piano played by Dooley Wilson in Casablanca sold at auction for $3.4 million in 2014. And that's without the transit papers. They sold separately for $118,750. (Source.)

Bergman's daughter says that things were a little tense on the set of Casablanca. (Source.)

That plane at the end taking Victor Lazlo and Isla to freedom? It's a scale model in order to fit on the set. The crew seen around it are little people, there to help sell the forced perspective illusion. (Source)