While the basic plot is the same in the movie as in the book, there were significant changes. Noting these substantial changes, in the commentary track on the DVD release, Tom Clancy jokingly introduced himself as "the author of the book that he [director Phil Alden Robinson, who is present with Clancy] ignored" and spending most of the commentary poking fun at the film's factual inaccuracies and differences from the source material. Perhaps the largest change were the original terrorists. In the novel, they were Arab nationalists, but in the film, they were changed to neo-fascists. A common misconception is that this was done as a reaction to the September 11, 2001, attacks, but the movie finished filming in June 2001.