To create the right physique for his role, Gong went on a diet for three months to reduce his body fat. He learned the Russian martial art Systema for the film's fight scenes, and performed car chases, rock climbing and skydiving at the Han River without using stuntmen.
The film was partly shot in Puerto Rico in April 2013.
Gong Yoo was eventually cast, and the protagonist's name "Ji Dong-chul" is similar to the actor's birth name, Gong Ji-chul.
Yoon Kyesang was originally cast in the lead role, but dropped out after costar Choi Min-sik left the project.
In behind the scenes footage it is shown that lead actor Gong Yoo has trouble pronouncing his brief Spanish dialogue in the scene set in Puerto Rico and requires several takes. The scene used in the film shows him speaking but it is shown from the angle of the back of his head. This is commonly done when the actor is not speaking the line themselves and either they dub it later in editing or another person dubs the line.