Towards the end of the movie when Colin is walking with Primrose through to the garden in the competition, her necklace varies between shots.
After the men lose the competition, they are invited to meet Her Majesty, and one of the officials says "Yes, HRH!" HRH stands for His (or Her) Royal Highness, which could mean Charles, William, or another of the Royal Family other than the Queen. The Queen is addressed as "Your Majesty" (or "Her Majesty," which is abbreviated HM).