Continuity mistake: During the wedding, there are flashes of the different people from throughout the story. In the one showing Lady Catherine and her daughter, in the first shot, Anne can be seen sitting very close to the arm of the sofa, but in the zoom out, she is further along.
Suggested correction: This is just a distortion of perspective because of two different camera angles. If you look at the pattern on the sofa upholstery you can see she is sitting in the same spot in both shots, midway between two vertical panels with red borders.