The first three characters of the VIN are TPL. The "TP" means the car was manufactured in Czech Republic.
When Captain Stottlemeyer is standing against Monk's bookcase, you can see the book "Blind Faith" by Joe McGinniss. It is a true crime story based on the 1984 case in which American businessman Robert O. Marshall was charged with (and later convicted of) the contract killing of his wife, Maria. The book was adapted into an television miniseries of the same name in 1990 (Blind Faith (1990)).
Tim Bagley who plays Harold Krenshaw, also appeared in Tony Shalhoub's show Sons and Lovers (1996) as Luke.
In the hospital hallway when Harold (Tim Bagley) and his cousin Joey (David Koechner) and looking at the children's drawing they mention the monster Mothra from the Godzilla franchise. David Koechner played a Mothra-like creature in the show Stan Against Evil (2016) (Larva My Life (2018)).
Real-life daredevil stuntman Evel Knievel (whose Get Well card to Harold features) died just a few months after this show aired. During his long-distance bike jumping career, he crashed 20 times. He still holds the Guinness Record for the number of bones he broke.