Two lessons here:
First, watch the umpire and see where he is looking on the foul pop-up. I'm usually quite critical of TV/movie umpires because they are absolutely terrible with mechanics. This "umpire" watches Costner the entire trip and lets the catcher take him to the play.
Second, it is quite obvious, box or not, no one is safe. The batter was in the box,
But where was the bull?