From the time that Chance underwater in the pool shoots Prentiss' second man, to the point where he aims a gun at Prentiss. only four seconds elapse. In that time he fully emerges from the pool, brings a muscular struggling man with him, stands fully erect, and aims a gun with a steady hand. Not only that, but he does so without making any audible splashing noise. And he takes the time to have tied the rope around his hostage's leg, since he wouldn't have done that until after he had shot the other two men.