What is meant by a comment that is described as incendiary

What is implied in this sentence from mark twain's "the £1,000,000 bank-note"? i was puzzled, and wanted to discuss the matter a little further, but they didn't; so i took my leave, feeling hurt and insulted to be made the butt of what was apparently some kind of a practical joke, and yet obliged to put up with it, not being in circumstances to resent affronts from rich and strong folk.

Why do you think frank tashlin titled this story  the bear that wasn’t? why didn’t the factory officials recognize the bear for what he was? why did it become harder and harder for the bear to maintain his identity as he moved through the bureaucracy of the factory?

2. page 1: schlosser describes "just another gorgeous rocky mountain vista. and yet cheyenne mountain is hardly pristine." why do you think schlosser describes the beautiful cheyenne mountain scene in detail before describing the military installation that lies inside?