Continuity mistake: When Lila gets the note that was taped to her door, she holds it by the side in the close-up showing the contents of the letter and from the top when she is crumpling it up. (00:15:30)
Continuity mistake: When Reid and Lila are in the pool, kissing, he explains how it is wrong that they are out in the open, and in a pool. Lila then kisses him again, and the paparazzo in the bushes takes pictures. In the first shot of this kiss, a close-up of Reid and Lila, her arms are down by her sides, but when seen through the camera, her arms are suddenly around his neck. Back to a close-up, and her arms are once again down in the water. (00:25:30)
Continuity mistake: When Reid tells Lila that her manager is dead, he has his hands on the back of his neck. When the shot changes, his arms are now lowered and under the water. (00:27:00)
Continuity mistake: When Reid disarms Maggie, he has his hand on the gun but no thumb on the hammer. When the shot changes to Maggie's POV, he has his thumb on the hammer. (00:37:20)
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