Pete announces the game as straight pool, but Jimmy sets up the game as if it was 8-ball. You can see him pull a ball out of the 8-ball position and replace it with black 8-ball. In straight pool there is no specific spot for an 8-ball.
Jimmy puts the balls in the rack, placing the 8-ball in the middle. When he lifts the rack the balls are now in a different order, including the 8-ball, now on the side.