Trivia

Song Joong-ki and Song Hye-kyo, who played the lead roles, married on October 31, 2017. The couple divorced July 2019.

Actor Song Joong-ki got injured while filming. Had to take 2 weeks of break before returning.

Yoo Ah-in makes a cameo appearance in one of the episodes. Song Joong-ki and Yoo Ah-in previously starred together in Sungkyunkwan Scandal (2010).

According to local reports by Newsis, lead actor Song Joong-ki was not the first choice of writers and directors for the hit South Korean series, as he was deemed too slender for the role of a heroic special forces officer. Song was later cast as the producers decided to change the character of the role. The 6th June episode of tvN's The List 2016 revealed the names of four actors who rejected the role before Joong-ki was chosen. As per the show, the A-listers who passed the role includes Won Bin, Zo In-sung, Gong Yoo, Hyun Bin and Kim Woo-bin. Reportedly, the actors were skeptical on sporting the army style short hair. It is also said that the artists expressed slight discomfort on portraying a role of a soldier and could not commit with the pre-production format of the show.

Filming took place in Greece for about a month from September 28, 2015. Main characters played by Song Joong-ki and Song Hye-kyo meet for the first time in Greece.