Continuity: At the end of the movie, when Lilly picks up the briefcase full of money to flee Roy's hotel room, several bills can be seen sticking out of the briefcase. However, in a previous shot, where she closed the briefcase and set it on the floor, these bills were not visible.
Continuity: In the train, when Roy is grifting the sailors, you can see that he is only rolling one die at a time. However, you can distinctly hear him drop two dice (out of the frame) to the table at the end of the game.
Boom mic visible: In the scene where John Cusack visits Angelica Houston in her hotel room to repay his medical expenses, there is an overhead mic clearly visible at the top of the screen.