Continuity mistake: The overall timeline of the film is about twelve months but it is inconsistent as far as the seasons. When Blomkvist arrives at the Vanger's island, it is the dead of winter with deep snowfall. A short while later, when Blomkvist is talking to the detective on a pay phone (who asks if he is surviving the winter weather), the snow is gone and the deciduous trees have no leaves, but a few minutes later, when the scene cuts to Henrik Vanger being rushed to the hospital, it is suddenly the middle of summer, sunny and the trees are in full bloom. When Lisbeth arrives on the island, and she and Blomkvist are sitting outside at night talking, the trees close to the house are bare and a howling wind can be heard in the background, but the next day trees have leaves. Some weeks later, when Lisbeth saves Bloomkvist from Martin, it is winter again, with heavy frost on the ground and trees are bare once more. A little while after that, when Lisbeth and Blomkvist go to find Harriet, trees on the street are in full bloom. A day or two later, when Blomkvist is talking to Harriet in the park, it is apparently now early spring because the smaller deciduous trees are only just beginning to sprout new leaves while some bigger ones have none at all. At the very end, it's just before Christmas again.
Other mistake: In the scene where Lisbeth gets off her bike before going up for her meeting with Dirch Frode and his associate, if you look at her helmet quickly as she's taking it off, her mohawk is perfectly intact, showing no sign of being squashed by her crash helmet. (00:06:15)
Factual error: In the very last scene, Mikael and Erika get into a taxi and head off. This is on Bastugatan in Stockholm, and they are heading west. Bastugatan is a one-way road, and you can only go east. (Go to Bastugatan 14, Stockholm, Sverige and look west, the scene is very distinctive, as is the Do Not Enter sign.)
Factual error: In any shot of a laptop screen, the operating system shown is Mac OS X 10.4, which was never available on any of the unibody MacBooks shown.
Continuity mistake: When Lisbeth searches Hans-Erik Wennerström on Google, the first search result is for a Wikipedia article. Below the link, Hans-Erik's birth date is listed as May 29, 1952. Lisbeth then goes onto the Wikipedia page and Hans-Erik's birth date is now listed as 12 June, 1951.
Factual error: There is no consistency in how written language is shown. Sometimes, like the check Bjurman gives to Lisbeth, on Swedish websites, or outdoor signs, they are written in Swedish. Other times, like the documents in the Vanger Corp. Archives, or the Swedish newspapers, and TV news graphics, it's in English. While many middle-aged and young Scandinavians have learned English in school, it is only used in specific circumstances and not for general, everyday use such as TV news or newspapers.
