Continuity: When Mr. Collins introduces himself to Mr. Darcy, Mary is behind them, talking to her parents. However, you can hear Mary singing at the piano (in the next room) at the same time, and then go on to see her there in the next scene.

Revealing: When Darcey has caught up to Elizabeth in the end and they are kissing in the street with the police cars around them, if you look at the side of the cars, you can see that these Las Vegas, Nevada police officers are driving cars from the Provo, Utah police force (where the movie was primarily filmed).