Character mistake: Mrs. Reynolds, the housekeeper at Pemberley, refers to Mr. Darcy's late mother as Mrs. Darcy while showing Elizabeth and her aunt and uncle the house. This is a grave mistake on the part of the filmmakers as she should have been referred to as Lady Anne, the way her sister is known as Lady Catherine. Their father was an Earl, making them Ladies by birth, not by marriage. Hence, they must be called Lady followed by their first name.
Other mistake: In the scene where Mrs. Bennet is thanking Col. Foster for his kindness to Lydia for taking her to Brighton, the camera pans out while Mrs. Bennet is still speaking. If you look at Mrs. Bennet and Col. Foster from that shot, it shows Col. Foster speaking to Mr. and Mrs. Bennet at the same moment. Mrs. Bennet could not possibly be speaking at that time.
Continuity mistake: In the scene at Pemberley when Darcy gets ready to dive into the pond, notice that in one shot, he is looking at the pond, the next shot shows him stepping down, and the third shot (right before he dives) shows him looking at the pond again - in the exact same place as the first shot, as if he never took the step down.
Continuity mistake: On disc 2, in the scene where Hannah is leaning out the window to tell Lizzie that the two gentlemen were waiting for her, you can see two gentlemen riding up the lane behind her. As the shot changes to Lizzie's face, they pass her. Then, when the shot changes back to both Hannah and Lizzie, the brown horse passes her again.
Plot hole: In Pemberley, Caroline Bingley refers to an utterance of Darcy ("I should as soon call her mother a wit") that he made after coming home to Netherfield after their first ball in Meryton. Falsely she says he made this expression "after they had been dining at Netherfield". This is a direct quotation from the novel and is not coherent with the film plot in which this utterance is made after the first ball.
Continuity mistake: In the scene where Lizzie is reading Jane's letters, telling her that Lydia has "thrown herself into the power of Mr. Wickham", she leaves the letters on the table standing next to her, in order to go and search for Mr and Mrs Gardiner. However, a few shots later when she's sitting at the table with Mr Darcy, the letters are neatly composed on top of each other. It's very unlikely that she left the letters that way.
Continuity mistake: In the outdoor scene at Pemberley, when Darcy is showing Mr. Gardner the good spots to fish, Darcy turns away and starts to walk with Lizzie up a path with the Gardners starting to follow. The camera changes to another angle and now Lizzie and Darcy are several terrace levels up the path (much further along the path than before) as they start talking.
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.
Factual error: During Lizzie's visit to Rosings Park, Lady Catherine presses her to stay longer, saying that if she will stay another month, she will be able to accommodate Lizzie "on the barouche-box" as far as London. This is nonsensical. What Austen actually wrote (Ch. 37) was: "And if you will stay another month complete, it will be in my power to take one of you as far as London, for I am going there early in June for a week; and as Dawson does not object to the barouche-box, there will be very good room for one of you. . ." The box is the coachman's seat on top of the carriage. Dawson is a servant, but if there were enough room inside the carriage, she would ride inside. What Lady Catherine is doing is offering Dawson's inside place to Lizzie. But in the movie, she is offering to let Lizzie ride outside next to the coachman. Not much of a treat.
Audio problem: When Lizzy, her aunt and uncle are in the tavern dining room discussing whether or not they should visit Pemberley, pay very close attention when Lizzy says, "We've no business there." The pitch and tone of the voice sounds completely different than Jennifer Ehle's. It sounds like it was dubbed.
Continuity mistake: At the end, where Darcy is making his second offer of marriage, Lizzy starts off with:"You must allow me to tell you how grateful I am." Look at the horses in the back: they are right behind Colin and Jennifer. In the next shot however, the horses are much further behind. One of Colin's lines has been cut out: when you read the book, Darcy says between Lizzie's lines something like: "I didn't know your aunt could not be trusted."