In most of season five, Amanda Righetti (Grace Van Pelt) was pregnant. Since it didn't fit in with the story line, she can only be seen sitting behind a computer or in dark shadows in almost every scene, and doesn't go into the field.
Patrick Jane's personal car is an early 1970's model Citroën DS, manufactured in France from 1955-1975, and sold in the U.S. from 1956-1972. The DS was the first mass production car to offer hydropneumatic self-leveling suspension with an option for the driver to manually raise or lower the chassis at the push of a button.
Frequently, there is talk of putting out a "BOLO" on a suspect or missing person. This is an acronym for "Be On The Lookout", a term synonymous to an APB -All Points Bulletin, stating all the specifics of the person(s) searched for.
Red John's right-hand man, Oscar Cordero (Cor-DER-o) and his right-hand woman, Rebecca Anderson (an-DER-son) are the only two characters ever on The Mentalist with the word "red" frontwards or backwards in their name except for the three characters named 'Xander,' who were named after the actor who played Red john.
The name of Red John is taken from the name of the one-armed man in the TV Series The Fugitive. fRED JOHNson. Kimball Cho gets his name from Dr. Richard Kimble. Madeleine Hightower gets her name from the high tower in the ending of The Fugitive.
The only actor in the first six seasons, with one exception, to have the word "red" in his name, frontwards or backwards, is Xander (xan-DER) Berkeley, the actor who played Red John. This is reported to be on purpose as one of the reasons he was chosen to be Red John.
Many of the main characters on The Mentalist were given names taken from characters or actors/actresses (or objects) in a TV Series created by Roy Huggins. These include Kimball, Wayne, Grace, Bret and Brett, Thomas, Hightower, and a waiter named Gerard.
The trivia items below may give away important plot points.
Every episode title, until season six, episode eight, contains a reference to the color red, like "Paint it Red", "Scarlet Fever", "Russet Potatoes", or "Bloodshot". This is because Patrick Jane's nemesis is the ingenious, sadistic serial killer, Red John. Beginning with season six, episode nine, "My Blue Heaven", Red John has been caught, so this theme is discontinued.
Red John never made an attack, nor directly influenced the events of any season premiere. He never attacked, nor acted in some way, shape, or form in every single season finale. In general, the season premieres dealt with the repercussions of Red John's actions from the previous season's finale.
The series premiere and series finale are mirrored reversals of each other. Whereas "The Mentalist: Pilot (2008)" begins with Jane having lost his wife and daughter, "The Mentalist: White Orchids (2015)" ends with him and Lisbon beginning their new life as a married couple and her revealing that she's pregnant.
Xander Berkeley, who played Red John, was born the same year as the Happy Face Killer, Keith Jesperson. According to 'The Mentalist and the Search for Red John', this is one of two reasons he was chosen.