It's a common expression in film. And it doesn't necessarily refer to fire. One of the greatest challenges of filmmaking is the unbelievable orchestration of talents and industries that put it all together within just a few weeks. If you think about it, it's really amazing we pull it off at all.
There's always a mishap around the corner. Something no one forethought. There are just too many factors. Like the aproaching helicopter that accidentally fanned the spfx flames of the set, causing the whole set to burn down.
It reminded me of a disaster I watched go down in the shop. The set had called for a dozen or so 4'x8' sheets of brushed aluminum. The real stuff. It had to be shiny. It had been a budget squeeze; they were an important quality in the set.
The Painters had them all laying flat on the paint tables. They were varnishing them prior to construction installation. It was really important to varnish them first, because they were short on time, and it was much quicker and easier. The finish was tricky. It was super glossy.
As I was delivering some drawings, I paused to admire the vast shiny production. Then, WHOOOOOM! Someone from another department opened up the rolling double doors. A huge gust of autumn wind picked up all the dirt and leaves from outside, and in a big cloud of billowing dust, as if aimed right at them, it blasted the wet, super glossy panels with shit.