Factual error: The film consistently mistakes Absinthe ban with Thujone ban. The United States Food and Drug Administration (US FDA) lifted the ban on Absinthe in 2007, 13 years before the events of this film. Thujone is still banned, and Absinthe products must contain less than 10 mg/kg Thujone content.
Continuity mistake: When Grandpa shows his old phone to Sally the way he holds it differs between the front and back shots.
Factual error: After Maya Peters is brought into the recompression chamber because of an injury, the timer is shown counting down by hundredths of a second and skips from 1 to 0 without showing 0.99-0.01. (01:24:30)
Continuity mistake: Isaac is wearing tan or khaki pants but the video of him getting "beamed up" to the spaceship shows dark blue pants. (00:18:15)
Continuity mistake: Mikey and his friend are smoking the same inch-long joint by the back door which gets passed back and forth - no way they could keep holding/smoking it for that long given how short it was to start with. (00:04:50)
Plot hole: After the incident in Chemistry class, Adam was taken to the hospital where he was diagnosed with schizophrenia. Next, Adam found out that he was expelled from school. What happened during Chemistry class was attributed to Adam's "first psychotic break" - which would fall under a medical condition for which Adam could not have prevented or controlled. The Department Of Education has laws protecting students like Adam (Individuals with Disabilities Education Act or IDEA, enacted in 1975), and the school is required to meet the child's / student's needs. An Individual Education Program (IEP) should have been prepared for Adam by his school, so the expulsion served to further the plot. (00:06:00 - 00:06:30)
Visible crew/equipment: Sara is at the front door video intercom. As the man from the Department of Sanitation is leaving, you can see crew/equipment visible in the reflection. (00:27:15)
Factual error: TV reporters said "home invasions" and mentioned trying to find the people who were responsible for the "70 robberies." Lance (in prison), was talking to a woman who was going to write a book and told her he got "twelve years" for "fifteen counts of robbery and vandalism." The crime Lance and the rest of the group were committing fits the legal definition of "burglary" in Illinois (basically, entering an occupied structure with the intent to commit a felony or theft inside; the structure does not have to be occupied at the time of the act). Because there happened to be someone at home during their last (intended) "burglary", this offense would be classified as a "robbery."
Other mistake: In this film, when they find the picture of Nancy (from the original Craft film), the image is of Nancy in the restroom of the original movie. If you watch the original film, the image that was used of Nancy shown in the new film would have taken place during the scene where Nancy, Bonnie, and Rochelle confront Sarah about wanting out of the coven. But during that scene, no cameras were in sight and nobody was taking pictures.