Continuity mistake: When the killer's truck drives off the bridge, the right headlight gets destroyed and goes out during the roll. A few seconds later, it is lit again. (01:55:35)
Factual error: During one of Blomkvist's flashbacks to his childhood with his babysitter (about 40 years ago), he is wearing Lightning McQueen shoes.
Visible crew/equipment: During the trip on a train, a camera is visible in the window.
Continuity mistake: During Lisbeth's first meeting with her new guardian and since questions about sex, her head positions are different between back/front shots.
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.
Revealing mistake: When both Lisbeth and Mikael open their Apple Mac computers and use them, the little apples on the outside should light up, but they don't - neither computer does; they're switched off or not powered up - Mikael even goes to the trouble of connecting his to a power cord.
Factual error: When Mikael goes to visit Henrik in hospital, Henrik's IV bags are far too low for the IVs to drip.