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.
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.
Visible crew/equipment: During the plane interior scene after the opening credits as JJ is walking around handing out documents to the team, you can see a gap in the lighting outside and a crew member's face peeking out from behind the white walls. (00:04:00)
The Fisher King: Part 1 - S1-E22
Continuity mistake: Agent Anderson (who takes Elle to her house) puts on his jacket twice.
The Fisher King: Part 1 - S1-E22
Visible crew/equipment: When Elle arrives back at her home the camera pans and you can see the face of a man in the mirror. A man who is not the Fischer King as he has no facial burn marks on him. Potentially simply a stand-in for the character or the actor without the makeup as when the Fischer King is going to shoot Elle you cannot see his face.
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 her 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