Three of the main characters were the same actor, and yet there are shots with all of them in the same scene. When I saw this as a young adult I didn’t even notice that Mike Myers was playing three roles and was genuinely dumbfounded years later when I found out.
How did they do those scenes so seamlessly?
Here’s a Captain Disillusion VFXcool episode about this special effect, specifically as applied to Back to the Future (which innovated having a split screen with a moving camera): https://www.youtube.com/watch?v=rhNDsPMaK_A