When does it become apparent it's all a dream in "The Occurrence at Owl Creek Bridge"? Is there reason to be suspicious before the last line of the...

It isn't
certain that this was all just a dream until right at the end of the story. But before then,
there are one or two clues. For one thing, we're told that Payton lost consciousness before he
supposedly fell from Owl Creek Bridge into the water. This would suggest that this is nothing
more than a dream.

Then, when Payton eventually drags himself out of the
water after being shot at by Union soldiers, he stumbles through what is described as an
interminable forest. Wherever Payton looks, he just can't seem to see any breaks in the trees.
Payton never realized that he lived in such a wild region. That's because he didn't; the wild
forest is simply a figment of his imagination.

As is the wide road which
Payton finally reaches. He's certain that it will lead him home to his family, and yet it seems
as if no one's traveled on it. For good measure, there are no fields bordering the road, and no
dwellings to be seen. Once again, this would suggest that Payton, far from having escaped the
clutches of the Union Army, is in the middle of a dream as he stands on Owl Creek Bridge about
to be executed.