The ending for the film was re-shot, due to poor test audience reception.
The film takes place over the course of a few days, but in the novel the story takes place over approximately two years. Also, in the book Alex Cross is 38 years old with two kids, whereas in the film he is in his mid to late fifties.
Morgan Freeman's second and final appearance as Dr. Alex Cross. Tyler Perry would later take over the role in Alex Cross (2012).
In the book, the Secret Service is protecting the young boy, and Alex Cross is forced onto the case, not drawn in. Also, he doesn't have a female partner as in the beginning of the movie.