Character mistake: Rossi reacts upset to the phone call before the killer starts singing happy birthday. (00:06:25)
God Complex - S8-E4
Character mistake: Spencer says that leg transplants are medically impossible, however, there was at least one documented successful double transplant performed a year before the season aired.
Character mistake: When Derek and Rossi are in the morgue, you can see the "corpse" swallowing just before the scene changes.
Magnum Opus - S8-E13
Character mistake: At the end the murderer says Van Gogh only sold two paintings before he died. Van Gogh only had one of his paintings sell before he died.
Character mistake: Unsub calls his victim Marcy, her real name, as opposed to Rose who he believes she is.
Character mistake: Close to the end of the episode, Dr. Reid says to the psychotic guy that was holding hostages, "M-theory cannot be proved." It should be "proven, " not "proved." Dr. Reid is supposed to be a genius, so he should be the last one to make such a mistake.
Character mistake: When Blake is telling Spencer to keep his eyes on her after being shot she calls him Ethan twice. (00:02:29)
Suggested correction: This is very poignant and deliberate moments in the dialogue. Blake is feeling distraught since Reid pushed Blake out of the way and took the bullet instead of her. Blake calls Reid by her dead son's name, "Ethan," when she tries to keep him alert and shouts, "Ethan, Ethan!" Later in the episode, when Blake takes Reid back to his apartment, she explains that watching Reid when he was hurt touched a nerve. Reid then asks Blake, "Who's Ethan?" and Blake tells Reid all about her son "Ethan" who died when he was 9 years old. Blake then tells Reid that "Ethan" would have been a lot like him. Note, on the jet return flight, Blake texted Hotch her resignation from the BAU, and at the very end she leaves her badge with Reid.
Character mistake: Dr. Reid calls Penelope "Kristy" on a phone call.
Suggested correction: He calls her "Garcia."