Factual error: The train car in which Elle and the other passengers are held hostage is supposed to be an Amtrak type long distance railroad car traveling from El Paso to Dallas, yet on the inside of the car we can see a large poster showing the Washington, DC Metro system map.
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.
A Real Rain - S1-E17
Factual error: When BAU walks up the stairs on the way into the courthouse the first time, the John Ferraro building in Los Angeles is visible in the background. They are walking up the stairs toward Los Angeles City Hall. The episode takes place in New York.
Factual error: In the episode, the case is handled locally by the Wilmington Police Department. In reality, Wilmington Police only operate within city limits. Based on the suburban locations pictured, this case would more likely be handled by Delaware State Police or New Castle County Police.
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