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)
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."
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