When Ray and Sydney go to Ray's house, Sydney is taking a video (on her smart-phone) of them walking up to the house. She films Ray's father and says "Say 'cheese,'" and we can see her finger over the lens. However, in the next shot, we see that she is only holding one side of the smart-phone, with one hand, and the lens is on the other side. Thus, there is no way her finger could be covering the lens.
Dropping a lit cigarette into a pool of gas will not ignite the gas. You need a flame or a spark to ignite it and the gs does not ignite it is the fumes.
The setting moves from Washington to North Dakota over the course of the show, yet the weather never changes. If the story was supposed to be set in Devil's Lake, ND in January, there should be 2 feet of snow on the ground.
When Morgan approaches the door of the gas station to deliver alcohol to the unsubs, the male unsub wields his Beretta pistol and an audible click is heard, presumably due to cocking the hammer. In subsequent scenes the pistol is shown uncocked and the safety lever is still on.
The captions show the last instance of Syd's name being spelled as "Sid."
When the team is in Spokane, WA, you can clearly see palm trees in the background. There are no palm trees in Spokane.
The opening scene following the credits is supposed to be in Billings, Montana. There are numerous palm trees visible in the background, however, which would never survive a Billings winter. A quick shot of a road sign in the same scene showing "Erringer Road" reveals the true location, namely, Simi Valley west of Los Angeles.
The Montana Record pulled up by Garcia shows that the female unsub was born in Oct. 1985 and was taken from her parents home by family services due to abuse in Aug. 2006 and placed in foster care the following day. (She would have been a 20 year old adult at the time, just 2 months shy of her 21st birthday.)
When Prentiss receives a text from her old friend Sean, his name is spelled wrong in her contacts. It reads "McCallister" when it should be "McAllister."