Other mistake: At the start, it's nighttime when the unsub hides in the house of the soon-to-be victim who goes to sleep when her alarm clock reads 'Tue 11:06', and then we see the time morph to 'Tue 1:13' when the victim is sound asleep, before the unsub comes out of the closet to kill her. However, the time on the clock should actually read 'Wed 1:13.'.
Other mistake: When Prentiss and Morgan are trying to figure out how the victims were controlled, Prentiss phones Garcia to find a drug that would temporarily paralyze or subdue. Then just as we hear Garcia answering the call, there's a close-up of Garcia's computer screen and we see the picture of five suicide notes, and at this point there have been six victims. Then later, after the seventh victim is found, when Morgan holds the latest suicide note in the close-up, we can see it's the same note that's already been shown.
Other mistake: At the start, the soon-to-be victim gets off the A train at Spring Street (subway heads south, then Bklyn/Queens) and stands on the west-side platform, facing the southern subway exit, then the unsub comes up from behind him, shoots him and he falls toward the same way that the unsub walks - the southern exit. However, when Hotchner plays the NYPD's surveillance footage, the victim is facing the northern subway exit when the unsub comes up from behind him, shoots, and he falls toward the same way that the unsub walks - this time the northern subway exit. Interestingly, neither are flipped shots since we can see "Spring St" correctly. Later, when Prentiss reviews footage it's as it was shown originally.
Other mistake: Just after they were finished explaining that you can not tilt the mystery package because it would instantly blow up, they show the little girl at her doorstep holding the package completely tilted. Just when you think that means that this package now doesn't fall into the "explosive" category, they then show the mom freaking out, and later police making the girl hold the package in a completely different (non-tilted) position.
Other mistake: When the character is buried alive the psychiatrist pours bags of dirt on the head of the victim. First, there is a pile of bags that shows only 8-10 bags of dirt, which is not enough to fill the hole. Secondly, the victim was conscious and standing up with no apparent broken bones, which means she could have just stood on the dirt as it was (very slowly) poured in. Additionally, she was buried completely during the entire time the murderer was evading police, having a conversation with Hotchner, and jumping to his death. Then the BAU talked about their suspicions she was still there and had to make it all the way to the basement. She would not have had a "faint pulse" after all of that time.
Other mistake: While Hotchner and Reid are talking about Hollow Man and the Mill Creek Killer, Reid's going through the newspapers and when he figures out that the two killers have been talking to each other via the classifieds, there are two closeups of an ad's text. After Hotchner suggests using their relationship against them, Hotch says that Reid's fake ad will imitate Hollow Man's language patterns to send a message to the Mill Creek Killer. Then we hear Reid reading the fake ad they just placed in the classifieds, but the problem is it's the same ad that was shown in the closeups earlier, plus an additional line at the end - "here's my gift to you."
Other mistake: Demonology, Season 4, Episode 17. Prentiss pulls up to a bar and the shot shows her looking out of the car window. "BAR" is shown reflected in red on the car window, but it is readable from left to right under the closeup of Prentiss's face when we see her. The reflection of "BAR" should have been backwards since it's a reflection of the sign on the building.