No, it isn't just a hand. It is the filmmaker's hand. It is the hand of a non-Jew. It is the hand of someone who was never a Roman soldier. It is the hand of a human being who is acknowledging his own sin, his own guilt, his own role in this story.
like the WHOLE movie .... make Jews look like monsters.
Oh really? Does Jesus (a Jew, and God himself, to boot) look like a monster in the movie? How about his mother? What about the girl who tries to bring him water? Nearly every protagonist in this film is a Jew.
But I guess that doesn't count, 'cause you don't want it to.