Continuity mistake: During the episode when Claire and Phil do their warm-up before racing each other, their children Alex and Luke arrive from school. They get down from the car, and the car takes off and goes away. But in the 2nd shot we can see that same car parked in front of them. (00:17:00)
Continuity mistake: In episode 11 of Season 4, it was stated that Leonard got an A in 1968, then opted for pass/fail to have the highest GPA in the college. In the final scene of this episode, however, it shows Greendale college as being established in 1974.
Continuity mistake: Tara is sitting at her desk and tells Max they will have sex the following night, and she teases him that she "Might even bring some props." Right as she says this line, the camera cuts. In the first shot, she has one pencil in each hand, but in the second shot, suddenly both pencils are in her left hand. The position of her hands changes between cuts as well.
Factual error: When browsing for information about the crow deaths in the Ganwar Region of Somalia, the computer indicates that the CDC requested additional funding from DHS. The only problem with that is, DHS was formed in 2002, 11 years after the incident in Ganwar. (00:40:05)
Plot hole: Bonnie is the anchor for the other side and feels when supernatural beings die. How come she didn't know Katherine wasn't dead? Did she never think it was suspicious that she never felt Katherine's body after she died?