The original English-language script by David Lesser was set in Texas and intended for the U.S. market. It was first translated into Chinese and then adapted for a local market. When director Renny Harlin came aboard, the Chinese-language adaptation was translated back into English. Harlin then read the original U.S. version of the script and brought on his own team of young film students (with the knowledge of Asian culture and customs) to rewrite it. The "new" English-language script was written simultaneously with the "new" Mandarin Chinese version (which was also translated into Cantonese).
The film is set in Hong Kong, but the interior of the morgue was built in the China Film Group studios in Huairou District in northern Beijing.
In June 2017, it was announced that Renny Harlin would direct an adventure-thriller "The Hanging Coffin" (from a script by Anthony Jaswinski) and an action film "Operation Somalia" in China. During post-production of Bodies at Rest (2019) in May 2018, Harlin and producer Daljit DJ Parmar formed a China-based production company "Extraordinary Entertainment". Their first announced project was a sci-fi-disaster film "Solara" (written by Creighton Rothenberger and Katrin Benedikt). Harlin lived in China until the COVID-19 pandemic closed the country in January 2020.
A Hong Kong actor Nick Cheung originally spoke his lines in Cantonese, while his Chinese co-star Zi Yang spoke Mandarin Chinese. Both memorized each other's lines to know how to respond to dialogue (later dubbed in their respective languages).