In the second season, Gary instantly calls out a psychic to be fake, claiming they're not real. James Roday's best known for his role in Psych (2006), playing Shawn Spencer, a fake psychic
The shirts that Maggie wears in earlier episodes reflects her Chicago roots. In later episodes, she is seen wearing shirts from Boston area sports teams.
Three of the actors playing main characters also starred as main characters/detectives in crime dramas for several years prior to this show: David Giuntoli (Eddie) as Detective Nick Burkhardt on Grimm, James Roday (Gary) as private detective Shawn Spencer on Psych, and Grace Park (Katherine) as HPD Lieutenant Kono Kalakaua on Hawaii Five-0.
The production used Wendy Poole Park in Vancouver in season 2 but used CGI to change the name on the Park's engraved rock sign to "The Francois Lawson-Rodriguez Park". This is likely a reference to the real-life couple of James Roday Rodriguez and Maggie Lawson (Psych's Juliet).
James Roday Rodriguez previously worked with Romany Malco on Miss Match (2003), Floriana Lima on Psych (2006), Allison Miller on Psych 2: Lassie Come Home (2020), Christina Ochoa on Blood Drive (2017), Sam Huntington on Psych: The Movie (2017) & Rolling Kansas (2003), Sutton Foster on Gravy (2015) & Psych (2006) & Into the Dark (2019), and Richard Kind on Miss Match (2003) & Psych (2006).