Assassination (2015) filmed in both Shanghai and Seoul for five months. A special set of 13,500 square meters was created in Goyang, Gyeonggi Province, to recreate the Seosomun Street in Gyeongseong. The rest of the filming took place at the Shanghai set in Chedun, which is 27 times the size of the Hapcheon set in South Gyeongsang Province (the 2007 Chinese film Gefahr und Begierde (2007) was also shot in Chedun).
On August 10, 2015, novelist Choi Jong-rim filed a lawsuit against director Dong-hoon Choi, production company Caper Film and distributor Showbox, alleging that various elements from Assassination, including the setting and the female protagonist, highly resemble those of his book Korean Memories, published in 2003. Choi is seeking 10 billion won (US$8.5 million) in damages, and an injunction to stop the film from being shown in theaters. Caper Film denied those claims, rebutting that the female character in Choi's novel is not a sniper, and that assassination schemes were common in the anti-Japanese movement. Seoul Central District Court rejected Choi's request for an injunction to stop the film from being shown in theaters, ruling on August 19, 2015 that an abstract summary cannot be protected by copyright laws, the female protagonists in the novel and the film are "depicted in completely different ways" with the assassination plan not a major plot point in the novel, and that supporting characters Kim Koo and Kim Won-bong are real historical figures and hence cannot be viewed as a source of similarity between the two works.
Lee Jung-jae, Jun Ji-hyun, Oh Dal-su and Choi Deok-moon previously starred together in Dodookdeul (2012), also directed by Dong-hoon Choi.