This slip-up is in the scene of the polo match. The first goal of the other team there is a person riding a horse toward the goal and you see the ball roll in. The goal that Chloe makes is the same shot, there is a person on a horse coming toward the goal with the ball rolling in.
If you watch the movie carefully you'll see that when the first shot is made in the polo game the horse in the back round is walking slowly towards the goal. In the second shot (the one Mary-Kate makes) the horse is now running towards the goal. It's not the same scene because the horse is now closer and is running towards the goal posts. Watch the movie again and you'll see. Sorry but close.