Other mistake: During Waverly's second chess match, her opponent says "check" (and play continues) even though it is checkmate.
Other mistake: Trying to impress his new relatives, Rich picks up, and then drops, a piece of rice with his chopsticks. Rich and Waverly act as if the rice has gone inside of his vest, but this would have been impossible since Rich was holding the chopsticks well away from his body. In fact, you can see the piece of rice bounce off of the table and to his left.