Continuity mistake: In the final hand, the first time we see Clancy's hand, it is the 8-9-10-Q of Diamonds; when the Kid calls, the cards are (a) reversed in order - Q-10-9-8) and worse, (b) throughout the entire movie, they are playing with Hoyle playing cards - but the reversed hand as well as Clancy's JD are from a deck of Bicycle cards, made by the United States Playing Card Co. In a real game, Clancy's hand would be dead, as it contains cards from an entirely different deck.
Continuity mistake: When The Kid comes in from walking in the rain, his clothes are soaked but his face and hair are bone dry.