Bierce's story and Farquhar's journey end with a simple, declarative sentence:
Peyton Farquhar was dead; his body, with a broken neck, swung gently from side to side beneath the timbers of the Owl Creek bridge. (3.20)
This, friends, is one heck of a twist ending. The final sentence compresses the time structure of the story and directs our attention to the strange nature of time in the story. Here we basically find out that the whole story takes place in the course of about one minute, or maybe just a few seconds.
Since we learn that Farquhar never falls through the bridge and down into the water, we have to reevaluate large portions of the story. What actually happens between the moment the sergeant steps aside and the moment Farquhar is dead? Just as Farquhar walks through a forest that he thinks should be familiar, we must return down the same road of the story that we thought we knew. This time, however, we have different and important information. Farquhar can't tell the difference between an imaginary escape and death by hanging. Bierce seems to ask, can you?