Factual error: During one of Blomkvist's flashbacks to his childhood with his babysitter (about 40 years ago), he is wearing Lightning McQueen shoes.
Factual error: Lisbeth is hacking a police database to find suspects. The camera shows her computer screen, where she's writing a query. The query shown asks for victims with specific initials for first and last name, but the results shown has other initials.
Plot hole: When the girl looks at the photos of Martin and his father while on the business trip, Martin is seen with his father and while wearing his boarding school sweater. But Harriet says later that he wasn't sent to boarding school until after their father was killed. Therefore, the sweater would not have been a clue in the earlier part of the movie.