When Blackie tears up the check, he only makes two tears. Later there are more than 4 pieces.
Blackie is a right-handed pool shooter. During the game when he is hustling Rob, one of his shots is made left-handed. Response: But many right-handed pool players have been known to make a shot left-handed. The reverse is true for left-handed players.
While Laura is watching TV in the living room the doorbell rings. As she crosses the living room to answer the door, you can see the shadow of, presumably, a stage-hand pass across the back of the TV set.
When Blackie breaks the balls and knocks in the 8 Ball, the 8 Ball was racked on the end of the bottom row. The 8 Ball is supposed to be racked in the middle of the third row of the balls.