Recently we were shooting a car interior night scene for one of my editing classes. It was a basic dialog scene, that we intended to shoot with three different camera positions.
First position was shot through the windshield of the vehicle.
Second position was through the driver's side window.
Third position was also shot through the driver's side window.
With time running out, we realized that it was going to take way too long to move the camera and reset the lights for the passenger's side window. So we did the next best thing. We had the actors switch places in the vehicle, and kept the camera and lights setup where they were and continued to shoot through the driver's side window. With a little luck, and a little "Flop" of the shot in post, the illusion came together.
Flop: This Perspective filter flip-flops the image horizontally, vertically, or in both directions at the same time. John Huston used this effect in his World War II documentary The Battle of San Pietro to keep the Allied forces heading right to left, and the Axis forces heading left to right, regardless of which direction they were actually moving during filming.