Trivia: A real wildfire occurred at the Fox Ranch M*A*S*H outdoor set, located in Malibu Creek State Park, destroying the entire set. The fire was filmed, and the producers and writers decided to incorporate the fire in the reworked script for the series finale.
Trivia: Most of the time in the series, when they're filming on the sound stage, you can see the apex of the roof, and the background behind it. But this time, they hung cargo netting that draped just below the top of the roof so that you can't see the background. This is also noticeable when you can tell that they're filming on location. There's no cargo netting at the tops of buildings.