Character mistake: When Tim and Ted enter the school, we can hear a group of girls including Tabitha singing: "The wheels on the bus go Pi-r-squared / circumference all around." But π r² equals the area of a circle, not the circumference (which is 2πr). (00:36:34)
Character mistake: Whenever Catherine visits the Baroness with young Estella, before she gets murdered, she asks the Baroness for money so that her and Estella could start a new life. Since Estella is being spoken about, the Baroness is aware of her at this point. However, later on in the movie, the Baroness questions John, "What did you think I meant when I said take care of the problem?!" Implying she thought Estella had already been killed when she was a baby.
Character mistake: After banker Karl was reported missing from his home, the police detective did not even think to locate his car - which he could have merely driven away in (meaning he was not kidnapped).
Character mistake: When Lydia texts Emily, her left index finger swaps between raised or not, depending on the shot. (00:12:15)