The original plan was for the film to focus on the terrorist's capture in Sudan in 1994 and run for 90 minutes. However, as director Olivier Assayas started conducting research into his subject, he realized that there was a much bigger story to tell.
In "Carlos", Edgar Ramírez plays the titular character, Carlos the Jackal. In the movie, The Bourne Ultimatum (2007), Ramírez plays an assassin trying to kill the titular character, Jason Bourne. In the Jason Bourne book series, of which the movie series is based on, Jason Bourne's nemesis is none other than Carlos the Jackal.
Olivier Assayas was initially not interested in the project as it seemed "too crazy and too complicated". However, his opinion swayed when he realized that he could make a film dealing with recent history and real people.