Continuity mistake: When the team is profiling the unsub, Reid's watch goes from being under his sweater's sleeve to being over it.
Character mistake: In the scene where the agents are called to the conference room and start talking about the case, the camera pans the room and shows a white board with information written on it. At the top of the board, in bold letters and asterisks around it, is the word MANDITORY.
Character mistake: In the meeting room, there's a clear spelling mistake of "Manditory" in bold letters on the whiteboard behind Gideon. Flashes up there several times during the scene. (00:16:00)
Chosen answer: Back in Target Rich, a hitman named Giuseppe Montolo dies whilst being interrogated by Derek. The men who abducted Derek were hired by his father, Chazz, who seems to blame Derek for his son's death. It's explained further in A Beautiful Disaster.
Annabel Keeley