When Cottonmouth first loses his hat in the swamp, it lands "right-side-up" on the water surface. In the next camera shot, as he is walking away the hat is now "upside-down" in the water. Finally, when Cottonmouth goes to retrieve his hat it is right-side up again.
The hat is not upside down. It has sunk so that only the crown is above water, forcing Cottonmouth to reach underwater to grasp the brim.
At the 0:06:30 mark as Walt and Ross go up the stairs Ross is talking but his mouth is not.