Garcia has to plot out the ages of Frank's kills for Gideon. When she reads them out loud, she begins, "He killed 43 in their fifties..." However, at the moment Garcia says "43," that information had not yet appeared on her screen.
Rebecca Bryant, the victim saved in "The Fisher King Part 2," returns in this episode. However, she is killed by Frank, which makes her the first person to be saved in one episode and murdered in a subsequent one.
This episode introduced Section Chief Erin Strauss.
Frank and Jane are hit by a fast-moving train at Union Station. Amtrak changes locomotives at Union Station, and the trains run north on electric engines and south on diesel engines. Therefore, a train would not be traveling through the station at such a high speed.
Reference to the "Smithsonian Institute" in this episode should have been correctly referenced as the "Smithsonian Institution." This is the second time this error has been made, the first being in "The Big Game."
Gideon lives at 181 Arthur Street.
When the prostitute is trying to find her way out of the building, she comes to an intersection between two hallways. She looks to her left, then to her right. When she looks to her right, a person's hand can be see on the left side of the screen.
When the unsub transports his victims to the kill room, he is whistling the song "Johanna" from the Stephen Sondheim musical Sweeney Todd: The Demon Barber of Fleet Street a musical about a serial killer. The words of the sequence he is whistling are:
I'll steal you, Johanna,
I'll steal you.
Do they think that walls can hide you?
Even now I'm at your window
I am in the dark beside you, Johanna.
Spokane, Washington, and the Boise National Forest are over 350 miles apart, which is an eight-hour drive.
In the scene with Prentiss, JJ and Garcia in a bar, the credentials Garcia flashes for Brad to read indicates she is a Supervisory Special Agent when she is, in fact, a Technical Analyst.
This episode presented the second time the BAU worked a case in Baltimore, Maryland. The team previously worked with Josh Cramer of the Organized Crime Task Force in the episode "Natural Born Killer" (Season 1).
About midway through this episode, the left ear of the kidnap victim has been severed from his body and delivered to his daughter. Later in the episode, the kidnap victim's left ear is still fully attached to his head, and there is no evidence it was ever removed.
Casting director Gina Garcia Sharp appears for the first time in this episode as CSU Tech Agent Sharp.
Thomas Gibson, Mandy Patinkin, and guest star Stacy Edwards all starred in Chicago Hope, although at different times.
It is revealed in this episode that Hotch's father had had lung cancer.
During the cold opening, the house is engulfed in fire, but no one inside the house has a cloth covering for their nose and mouth like a wash cloth. In fact, they are shown breathing without covering their mouths.
When Will LaMontagne, Sr. is talking to his son, he calls him "Billy." And when the team meets him, he introduces himself as Bill. However, in all future appearances, he is called "Will."
This episode marked the first appearance of Detective William LaMontagne, Jr., who was written in later as the father of Agent "JJ" Jareau's baby (Henry) when the actor herself (A.J. Cook) became pregnant in real life.
It is revealed in this episode that both Morgan and Prentiss are big fans of the writer Kurt Vonnegut.
The crimes in this episode are committed in Westchester County, New York. However, when the team and the local police apprehend the unsub in Mt. Vernon, the officers are driving NYPD patrol cars. The NYPD has no jurisdiction in Westchester County.