This film is based on the book by Gregory McDonald, which is the second book in the Fletch series. Fletch (1985) starring Chevy Chase was based on the first book.
Fletch says he quit journalism because the profession has been cheapened by social media. In the book, Fletch has retired and fled the US having secured a large amount of money from a corrupt businessman (as depicted in the original 'Fletch' novel/film).
As the thief breaks into the drawer under the fish tank, briefly the music from Fletch (1985) can be heard.
Tasserly pretends he needed medication to treat a condition he calls "Segegenesis". In his struggle to lie on the spot, he just altered the name of the classic console video game system Sega Genesis.
The character of Frank Jaffe does not appear in the novel 'Confess, Fletch'. He was a former editor of Fletch's, but he never worked in Boston.