Other mistake: When the character is buried alive the psychiatrist pours bags of dirt on the head of the victim. First, there is a pile of bags that shows only 8-10 bags of dirt, which is not enough to fill the hole. Secondly, the victim was conscious and standing up with no apparent broken bones, which means she could have just stood on the dirt as it was (very slowly) poured in. Additionally, she was buried completely during the entire time the murderer was evading police, having a conversation with Hotchner, and jumping to his death. Then the BAU talked about their suspicions she was still there and had to make it all the way to the basement. She would not have had a "faint pulse" after all of that time.
Factual error: In the scene where the two unsubs are in the restaurant choosing the next victim, the family they are watching is a Hispanic family that breaks from speaking English for two lines to speak in Spanish. The father asks where the daughter is going, and she answers, "A lavar mis manos," which means to wash my hands. This is incorrect. In Spanish, you would say this as "A lavarme las manos."
About Face - S3-E6
Continuity mistake: Senior SSA David Rossi is clean-shaven in the beginning and middle of the episode. Toward the end of the episode, which takes place over mere days, he has magically grown a full mustache and beard which disappears and reappears in the last scenes.
About Face - S3-E6
Continuity mistake: This episode is a flash back to when Agent Gideon joins the team, but agent Prentiss is already a member. She didn't join until season 2 (when agent Gideon was already an established character).
Continuity mistake: Reid moves his gun to his side after the militia tell him he is begging for someone to take it. You can see it after they send Morgan to the bar. One second it's on his side, the next second it's back in front off his hip like always. (00:23:15)
Visible crew/equipment: When JJ and Derek get to the bar to talk to Harris Townsend, while they're still outside in the parking lot, right after Derek tells JJ not to turn her back on the door, the reflection of the moving camera can be seen on the pickup's back window as they walk to the door.
Visible crew/equipment: When the trailer park manager leads Rossi and Reid to Goehring's trailer, right after he tells Reid, "Piece of advice, pipe cleaner, way you're wearin' that gun...beggin' someone to take it off you," the cameraman and camera cast shadows on Reid as he walks by the camera.
Continuity mistake: In the episode before this one, Garcia gets shot and the wound is over her chest. This episode starts when a woman finds her, and the wound is noticeably further down. (00:46:05)
True Night - S3-E10
Continuity mistake: When Garcia and Morgan are talking in Garcia's office, her hand on Morgan's chest disappears and reappears. (00:04:55)
Birthright - S3-E11
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. (00:18:45)
Factual error: When Garcia asks Reid about the IP address of one of the victims father's computer he says "374.54.12.3." On screen also the IP address of the router can be seen which reads "192.3.16.7894. Neither is possible. The numbers in any IP address can only range between 0 and 255, since they are actually 4 groups of 8 bits each. (00:10:45)
Visible crew/equipment: When Katrina Townsley's driving while talking on her cell phone the unsub is driving behind her, and we see that she's alone in her car, but when the unsub rear-ends her car the second cameraman is sitting in the passenger seat with a handheld camera, filming Katrina's close-ups.
Character mistake: At the end of the episode, Rossi quotes Anne of Green Gables author Lucy Maud Montgomery, but accidentally calls her "Lucille".
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."
Continuity mistake: When Rossi is telling Prentiss, Morgan, and JJ about the original Galen case, he says that the Galen parents were butchered with an axe, but in "Birthright", he tells Detective Caulfield that they were beaten to death.
Character mistake: When Emily Prentiss makes note of the 110 V outlet having no GFI, she calls it 'Ground Fault Insulation', when in actual fact, GFI stands for 'Ground Fault Interrupter'. (00:11:00 - 00:12:00)
Visible crew/equipment: When the team enters the house of the unsub it is dark. You can see a second camera man twice off to the side who is getting the close ups of the team coming through the door. (00:32:00)
Other mistake: When Garcia tracks down Peter Redding's current address, we see a close-up of Garcia's computer screen and the address reads "12859 Beckler Ln.," but when the BAU and police arrive at Peter's house the number is 4433.
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.
Answer: "The Boogeyman", s02e06. Spoiler alert: The kid is Jeffrey Charles and at that point he had already killed 3 other kids. Jefferey basically hated and resented other kids after his mother abandoned him and his father spent a lot of time with other children because of his job. Jeffery would lure kids Into the Woods and then beat them to death with his bat just because of hate, no particular "reason." The scene you're describing, Jefferey agrees to walk Tracy home when her "buddy" leaves her (at this point the FBI announced there's a serial killer on the loose and kids should walk with a buddy). Jeffrey gets mad at Tracy for walking too slow and for complaining, and he takes a swing at her, causing her to flee Into the Woods and have Jeffery chase her.
Bishop73