There is a deeper meaning to the name "Saja Boys." The Korean word "saja" can mean lion and we see that their logo and branding include lion imagery. However, in Korean folklore "jeoseung saja" are grim reaper figures who escort the souls of the dead to the afterlife. Typical depictions of jeoseung saja show them wearing a black hanbok and a gat (wide brimmed hat) just like the Saja Boys in their demon forms.
In an interview with Forbes, director Maggie Kang said that the Saja Boys "share the same CG body, except for Abby Saja, because he's a little bit bigger, we bulked him up like 20%."
The film's writer/director Maggie Kang makes a cameo early on as the flight attendant watering the plants with coffee.
In an interview with Forbes, director Maggie Kang did admit that the character of Jinu was inspired mainly by K-drama actors. She names Cha Eun-woo and Nam Joo-hyuk as the leading men on the inspiration boards. They wanted him to have a very classic Korean look, which is why he had dark hair. Though Ahn Hyo-seop was cast as the voice of Jinu, the character was created before he signed on for the part, but Kang does see the similarities with his Business Proposal character.
Director Maggie Kang revealed that the Saja Boys were inspired by Korean boy bands such as TXT, BTS, Stray Kids, Ateez, Big Bang, and Monsta X. The three members of HUNTR/X were modeled after K-pop girl groups like Itzy, Blackpink, and Twice.