The military coup took place on December 12, 1979, after the assassination of President Park Chung-hee. Major General Chun Doo-hwan, who led the coup, took control of the government and declared martial law. The military coup in 1979 and the subsequent political incidents led to a period of military rule and significant societal and political changes.
The film, 12.12: The Day, depicts events that happened just before and during the coup and the people engaged in it. Veteran actor Hwang Jung-min played Chun Doo-kwang, a Major General who orchestrated the coup. In the movie, Hwang was rivaled by actor Jung Woo-sung, who played Lee Tae-sin, the commander of the Capital Defense Command (formerly known as the Capital Garrison Command). The characters' names in the film were differentiated from their real-life role models. For example, Chun Doo-hwan's name was changed to Chun Doo-kwang, and Jang Tae-wan was changed to Lee Tae-sin.
The film's distributor Plus M Entertainment said on December 27 that its sales exceeded $1 million in North America. This is the highest record in the region in 2023, beating "The Roundup: No Way Out," directed by Lee Sang-yong with $910,000 in ticket sales. After hitting theaters in Los Angeles in late November, 12.12: The Day was released in some 50 theaters in North America including Minnesota and Alabama. According to data released by the Korean Film Council (KOFIC), the historical action film had an accumulated 11,003,251 admissions as of December 28.
Visual effects (VFX) technology was used to actualize the intense historical incident. VFX technique, which incorporates computer graphics (CG) elements, is often used by filmmakers to produce imagery that is difficult to film or doesn't exist in the real world. In the movie, dozens of tanks were moving around Gwanghwamun Square, an iconic square located in central Seoul, but only one tank was used in reality.