This is Catalina Sandino Moreno's film debut. An anonymous admirer who had seen her in a play told her mother about the open casting call.
Catalina Sandino Moreno became the first actress ever to be nominated for Best Actress at the Oscars for a role that it is spoken entirely in Spanish.
Although the first part of the film is set in Colombia, it was actually filmed in Ecuador.
Catalina Sandino Moreno prepared for her role by working in a Colombian flower plantation for two weeks cutting roses. She did not meet with real drug mules because she wanted to appear to be as clueless to the process and the consequences as Maria was.
Catalina Sandino Moreno did not practice swallowing pellets during rehearsals. Since the character of Maria did not know how to swallow them, Moreno and Joshua Marston agreed that it would be more realistic for her to try swallowing them for the first time on-camera. The pellets were made of easily-digestible substances, but neither Moreno nor Marston will reveal their exact composition.