The role of Ronald Niederman is played by Micke Spreitz. Spreitz got the part after the filmmakers' original choice Dolph Lundgren turned the role down. If Lundgren had taken the part it would have been his first role in his native country, Sweden.
In the early scene where the editors are meeting in the Millennium office, there's a pile of magazines. Prominently displayed is a copy of EXPO, the anti-fascist magazine Stieg Larsson helped found in 1995.
Of the three books/films in the Millennium Trilogy, this is the only one whose English title is a literal translation of the Swedish original. 'The Girl with the Dragon Tattoo' was originally titled 'Men Who Hate Women'. 'The Girl Who Kicked the Hornets' Nest' was originally titled 'The Castle in the Sky that was Blown Up'.
The trivia items below may give away important plot points.
Part of the plot of this film revolves around two involved, but unmarried journalists. Dag Svensson and Mia Bergman (Johansson in the book), who live together, are murdered because of the nature of their reporting. Blomkvist and his associates are then stuck with the ethical issue of what to do with their reporting, and how or if to finish their work for them. This quite closely parallels the life and tragic death of the author Stieg Larsson. Larsson lived with his girlfriend Eva Gabrielsson, but they were unmarried to avoid publicizing their address. Like Svensson and Johansson/Bergman, they worried about death threats. Though there was no evidence of foul play in Larsson's death, his Millenium series was unfinished. Like Svensson, he had a fourth book unfinished. Fighting between Gabrielsson and Larsson's family over the rights and royalties have left the rest of the series unwritten.