Corrected entry: In season 4, episode 9 "52 Pickup", in the scene where Jordan is describing the case, the writers made a large error concerning the M.O. of the UnSub. Agent Jordan states that the UnSub makes his victims clean up their own murders, and they arranged the cleaning supplies in a triangular pattern. The cleaning supplies were bleach, ammonia and garbage bags. This would be excusable if she hadn't also added that both bleach and ammonia were found under the victim's fingernails. If you mix ammonia and bleach, it has the potential to create one of three very dangerous chemicals. One was used in WW1 (chlorine gas), and the other two are highly explosive (Nitrogen trichloride and hydrazine). However, all the victims died of exsanguination (blood loss). This isn't mentioned by Dr. Reid, who has a Ph.D in Chemistry.
Corrected entry: Episode: "Sex, Birth, Death": 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. Was it MANDATORY for them to misspell this word?