The title of this episode ("Coda") refers to the closing section of a musical composition.
Guest-star Mimi Kennedy and Thomas Gibson starred together previously on Dharma & Greg, in which Mimi was Greg's mother-in-law Abby.
Molly wakes up as Jane is holding her in the lake while Prentiss calls to her. The next shot shows Jane looking at the agents on the bridge, but Molly can be seen still unconscious. When the shot goes back to Jane's face Molly is awake again.
Although red for the beginning of the season, Garcia's hair went back to blonde in this episode.
This episode was reminiscent of Stephen King's novel Misery, in which an obsessed fan kidnaps, holds hostage, and tortures a writer to force him to rewrite his latest novel. The book was later adapted to a film of the same name, which starred Kathy Bates and James Caan.
Sergio, the name of Prentiss' cat, is also a name that Hotch jokingly suggested to Haley as a name for Jack in the beginning of the pilot episode.
It is revealed in this episode that Reid speaks Russian.
This episode was reminiscent of Perfume: The Story of a Murderer (2006), in which a man who was born with a superior olfactory sense creates the world's finest perfume. Ultimately, his work takes a dark turn as he searches for the ultimate scent.
"Sense memory" is defined as the mental capacity or faculty of retaining and reviving facts, events, impressions, etc., or of recalling or recognizing previous experiences.
This episode was reminiscent of Natural Born Killers (1994), in which two victims of traumatized childhoods become lovers and psychopathic serial murderers who are glorified by the mass media.
Whether coincidence or intentional on the part of the network, "The Thirteenth Step" was the thirteenth episode of the season.
In the Alcoholics Anonymous program, the 13th step is a derogatory term that loosely refers to "hitting on newcomers." The phrase is most commonly used to refer to men who have several years of sobriety who make a habit of trying to date or take advantage of women new to A.A., but is not always limited to men.
In the first victim's home, Hotchner comments that the unsub turned the victim's crucifix upside down. However, this is incorrect. The object shown on the wall is a cross, not a crucifix. In order to be considered a crucifix, it must have some image of Jesus on it.
Reid takes off his FBI jacket in the room, then goes into the old house without wearing it. However, when he goes up the stairs to open the door, he has the jacket on, then in the house the jacket is gone again.
When James Stanworth is confronted by Morgan, he calls him "Congressman." However, Garcia had just uncovered that he was currently running for office for the first time and had not yet been elected.
Don Sanderson is a convicted murderer on parole and under arrest for a new murder. However, when he is taken to his former residence, he is not wearing handcuffs.
One of the props seen on Rossi's desk in this episode is a photograph of Joe Mantegna and Ringo Starr.
When Morgan is chasing Mary Rutka's assailant from her apartment, there is a shot of Morgan from behind after he runs in front of the car and he runs down an alley, and his gun is missing from its holster. In the next scene, his gun has reappeared.
When Garcia is speaking to Hotch and Rossi, she says, "Safe travels, mon ami." In the French language, this phrase should have ended mes amis.
At 23:25 Matthew Gray Gubler walks on camera, says his line, then tries to stifle a laugh. He looks at Rachel Nichols, who does the same. In the United Kingdom, this is called corpsing, which is a theatrical slang term used to describe when an actor breaks character during a scene by laughing or by causing another cast member to laugh.