In the famous plane scene at the end of Casablanca, they had to use some old school Hollywood magic to pull off the illusion of being at a real airport.
For security reasons during WWII they were not allowed to film at an airport after dark.
Instead they used a sound stage with a small cardboard cutout airplane. To give the illusion that the plane was full-sized, they used dwarf actors to play the ground crew. Check out the scene.