Continuity mistake: When the guidance counselor is addressing the community members, Reid is standing against the wall with his arms crossed, and then immediately after his hands are in his pockets, and you see him crossing his arms.
Continuity mistake: When the team is profiling the unsub, Reid's watch goes from being under his sweater's sleeve to being over it.
Continuity mistake: When Garcia accesses the bank's page online Prentiss gives her the account number login, 1552 9384 6729, and we see Garcia typing it correctly on the screen with the password, but when it cuts to the account's page showing deposit and balance, we see in the balance box the account number's last four digits are 7629, not 6729.
Continuity mistake: When Morgan gets off the phone after talking with Garcia about the list of chemicals he found, the hand holding the phone to his ear changes between shots. (00:13:55)
Continuity mistake: When Gideon, Morgan, Reid and Greenaway are watching Hotch interrogating the suspect Tony Canardo there is a box on the table, then Hotch gets up and walks out of the room and the box on the table is gone. In the next shot on the TV the box has reappeared. (00:30:08)
Continuity mistake: When the pregnant lady came in with her child saying her 8 year old Matthew was missing, JJ sits her down and says she has a niece who is 8. We later learn that JJ's only sibling was her sister who committed suicide and who didn't have any children.
Continuity mistake: When the team visit the home of Marcie Mitchell, the older boy takes the baby to another room. The baby is crying, then as they are in shot walking through the door the baby is looking around and smiling, and as the door shuts we hear crying again. (00:11:20)
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