Character mistake: After the murder that takes place while the team is at the church meeting, they gather together to talk about narrowing down the suspect list to the people who didn't show up to the meeting. Spencer shows up with a stack of papers and says 18 suspects didn't show up. We then see his actor break character and almost laughs when he looks over at Ashley, whose actress too almost breaks character from laughing.
Other mistake: JJ calls Hotch unsure if she can make direct contact with the unsub, fearing that she will make a mistake. Hotch tells her she will do fine and tells her that they are gathering background information about Flynn, who is the unsub. At this point the team have not yet figured out the identity of the unsub and Hotch should not know his name. (00:27:35)
Character mistake: When Reid and Rossi propose the theory that Kate knew Syd and Jimmy before her disappearance, and JJ expresses her skepticism, Rossi retorts "they're handsome, charming, 19." But while reviewing the case on the flight to Maryland, JJ mentions that the boys are both 20.
Continuity mistake: While Morgan and Prentiss are at the crime scene talking to the homeless man, when Morgan moves the tent and finds the text written on the wall, the homeless man smudges the text with his fingers, but when Morgan sends a photo of the evidence the smudges and text differ.