The room that Harrison was told to clean is 237 which is a reference to the movie The Shining.
The hospital Dexter Morgan is admitted to, is the same location as the jail Frank Castle was detained at in The Punisher season 2 episode 3.
Dexter uses the alias 'Dr. Patrick Bateman' to procure M99 (Etorphine) from a veterinarian. The name is a sly nod to American Psycho, where Patrick Bateman (played by Christian Bale) is a Wall Street executive who conceals his psychopathic alter ego and serial killer instincts behind a polished public persona.
Homicide detective Claudette uses headphones and music to mentally reconstruct murder scenes-a method reminiscent of FBI Agent Paul Smecker (played by Willem Dafoe) in The Boondock Saints, who also uses headphones and music to immerse himself in the psychology of the crime.
Marc Menchaca plays a ride-share serial killer known as 'Red'-a.k.a. 'The Dark Passenger'. Interestingly, his character in Ozark, Russ Langmore, also shares the nickname 'Red,' creating a subtle throughline in Menchaca's portrayal of intense and morally complex roles.