The title is intentionally polysemous: it refers to the nickname of the Thompson submachine gun used by the resistance fighters, the posthumous autobiographical novel written by Seo Hwi-young, the modern novel serialized by Han Se-joo, and the actual haunted typewriter discovered in Chicago.

Im Soo-jung's role as Jeon Seol marked her return to television 13 years after her 2004 drama 'Sorry, I Love You', and she revealed that, much like her character, she genuinely loves books and writing.

The Sapsali dog Gyeon-woo, who bonds Han Se-joo and Jeon Seol, is actually an Old English Sheepdog; the production team happened to meet the dog at a casting audition location for another dog and offered it the role on the spot.

Filming began on March 2, 2017, just about a month before the show premiered.

Scenes depicting 1930s Gyeongseong street life were shot at an open-air theme park in Hapcheon County, South Gyeongsang Province, while modern-day scenes were filmed at various Seoul locations including SEOUL SEOUL 3080, Hannam-dong Book Park, Ikseon-dong, and Seodaemun Prison History Museum.

For the key typewriter prop, the production team selected an English-language typewriter typical of the 1930s and had an expert retrofit it with Korean characters (Hangul); missing parts were only obtained and the machine modified a week before filming.

Han Se-joo's study was set with roughly 20,000 real books, and the layout of his writing room was designed to mirror the old storage space in 1930s Gyeongseong so props could serve as visual links between the past and present.

The 1930s-set scenes feature era-appropriate jazz music, including songs by Ruth Etting and Benny Goodman.

The song performed by Ryu Soo-hyun (Anastasia) at Carpe Diem is Park Dan-ma's 'Nal-la-ri Baram', which actress Im Soo-jung recorded herself; the OST tracks 'Come With Me' and 'Time Walk' were sung by Boni Pueri, a Czech boys' choir.

When the April 28, 2017 episode was preempted for a presidential election debate broadcast, a special 60-minute recap special condensing episodes 1-6 aired instead, narrated by Huh Ji-woong; a later behind-the-scenes special covering episodes 1-8 was narrated by cast member Go Kyung-pyo.