Character mistake: In the initial meeting at FBI headquarters, the agents mention the Zodiac killer. Gideon says about him "Yeah, and he killed for 30 years without being caught." In actuality, the Zodiac's known victims were killed between 1966 and 1970. In letters to the public, Zodiac claimed responsibility for several other murders (most of which were solved without being attributed to Zodiac), but no later than 1974. Gideon's statement was off by at least 22 years.
Continuity mistake: At the start of this episode Rossi tells Garcia about the case he's obsessed with, "It's the 20th anniversary of this crime. Twenty years tomorrow, three children woke up and found their parents murdered." However, during S3xE11 "Birthright," while working on their current Wilkinson case, Rossi shows Caulfield (the sheriff of the original Wilkinson case from 1980) the victim's charm bracelet he carries, then tells him about the Indianapolis case he's never forgotten, and how every year since then he's called the victims' children. And later, after Caulfield tells Rossi it's been 27 years since his own unsolved case, he asks Rossi how long it's been for him and Rossi says, "21," then Caulfield cautions, "Don't let it get to 22."
Other mistake: At the start, it's nighttime when the unsub hides in the house of the soon-to-be victim who goes to sleep when her alarm clock reads 'Tue 11:06', and then we see the time morph to 'Tue 1:13' when the victim is sound asleep, before the unsub comes out of the closet to kill her. However, the time on the clock should actually read 'Wed 1:13.'.
Visible crew/equipment: When Prentiss, Morgan, Rossi, and Caulfield go see Mary Wilkinson, in the wide shot just as Caulfield says, "Hello, Mary," the second camera filming from another angle is visible at the right side of the screen. Additionally, later when Chrissy confronts Charlie she's wearing one earring in her right ear, but after she shoots him that one earring is in her left ear.
Continuity mistake: When Cy sneaks into the house with the key under the mat, in the bedroom he picks up the triple gold frame with two photos of Matt with Lyla and one photo of young Lyla in the blue dress in the center frame, then he holds it to his face and places it back on the right side of the dresser. However, after Cy hears Lyla coming into the house, when she sees the underwear on the bedroom floor the frame on the right side of the dresser is now a double wood frame with only one of the same photos seen earlier.
Continuity mistake: At the beginning, a St Louis couple has reported their son missing. At the FBI briefing, the agents are told that the boy's mother tucked him in at 10:00pm. A few minutes later, we hear the radio call over footage of police at the home, and the dispatcher says "Last seen at 2100." That's 9:00pm, not 10:00pm.
Other mistake: When Prentiss and Morgan are trying to figure out how the victims were controlled, Prentiss phones Garcia to find a drug that would temporarily paralyze or subdue. Then just as we hear Garcia answering the call, there's a close-up of Garcia's computer screen and we see the picture of five suicide notes, and at this point there have been six victims. Then later, after the seventh victim is found, when Morgan holds the latest suicide note in the close-up, we can see it's the same note that's already been shown.
Revealing mistake: When Agent Hotchner receives a text from JJ while interviewing the suspect, it is actually a screenshot. You can see Camera Roll in the upper left hand corner, "2 of 2" where JJ's name should be, and the Share/Play/Delete banner at the bottom. It is covered by Agent Hotchner quickly tapping on the screen to clear the banners.
Character mistake: Derek Morgan says that he discovered the body of a dead boy in 1991 when he was 15 years old. Later on, you see Garcia searching the computer for personal info on Derek Morgan. According to the computer; Derek Morgan was born in 1973 which would make him 18 years old in 1991, not 15.
Factual error: In this episode Gideon mentions Andrei Chikatilo, and says that he lived in Ukraine (and that this is why he remained uncaught for so long). While Chikatilo was born in Ukraine, he lived in Russia for most of his life, and all of his murders happened here. An expert like Gideon should not make this kind of mistake.
Visible crew/equipment: When James Charles, the guidance counselor, says, "It could be someone you know, or it could be a stranger you pass at the grocery store," the actors' red T-marks are visible on the floor at Reid's and Gideon's feet. Then when Charles continues to say, "gathering information on the case," we can also see the actor's white T-mark beside the counselor's feet, where he will stand after he introduces Gideon.
Continuity mistake: In the elderly victim's home, when Gideon is going through the dresser drawers he finds the small frame with the picture of her son, and there is a blue frame lying in the drawer, but in the next shot that blue frame is lying on the dresser even though he never touched it.