There are references in the novel "Cross" to both Morgan Freeman and Tyler Perry. The reference to Freeman may be homage to his role as Alex Cross in Kiss the Girls (1997) and Along Came a Spider (2001).
Matthew Fox went through a strict diet and workout routine to gain muscle and lose a high amount of body fat.
Before the film was released, the studio announced that Tyler Perry would be reprising his role in "Double Cross". All talk of this sequel swiftly disappeared when this film tanked at the box office.
Idris Elba had originally been considered to take over as Alex Cross from Morgan Freeman. Author James Patterson supported the choice and Elba was keen to play the part, but the studio preferred a better-known American, and selected Tyler Perry instead. Elba had previously starred in Daddy's Little Girls (2007), which is directed by Perry.
In the Alex Cross novels, Alex's best friend and partner is John Sampson. In the movie, Alex's best friend and partner is Tommy Kane.