Park Chan-wook's inspiration for the film was the Swedish crime novel series "The Story of a Crime" by authors Maj Sjöwall and Per Wahlöö. The series follows the aging police detective Martin Beck and are known for their social critique. Park's pitch was "what if Martin Beck fell in love with a suspect?"
Director Park Chan-wook has mentioned that initially he didn't like the idea of using many text messages in the film. He even said that he considered making it a period piece, in order for the characters to write each other beautifully hand written letters instead of text messages on their phones. When he finally decided on a contemporary setting, when possible, he had the characters use a smart watch, voice recordings and translation apps instead of typing.
The complete Martin Beck book series, written by author couple Maj Sjöwall and Per Wahlöö, is visible on a table in a scene as a nod to the fact that Director Park Chan-wook have stated that he got inspiration for the film from those books.
The widow's wallpaper appears to be both waves on a sea and mountains, a dichotomy repeated symbolized throughout the film
Official submission of South Korea for the 'Best International Feature Film' category of the 95th Academy Awards in 2023.