The show filmed in real catacombs in Bulgaria.
The series filmed all ten episodes at once which is very uncommon for TV. The accomplishment
of this feat was attributed to the director, Oded Ruskin, as he was able to track all the story lines
at once.
Absentia was an extraordinarily difficult project because all 10 episodes were filmed
simultaneously based on location. It was filmed like a movie over three and a half months in the
middle of winter.
Lethal Weapon references appear in the show. Boston PD officer Tommy responds with his call sign 3 William 56 which was Murtaugh's and Riggs' call sign with the LAPD. Also, the family dog is named Riggs, which was Mel Gibson's character in the Lethal Weapon franchise.
Patrick McCauley is an English actor, he worked with a dialect coach in Los Angeles to master
his American accent. This was also Patrick's first time in America.