Character mistake: When Katie's husband arrives in town and confronts her on the night of July 4th, he says "I miss you Katie." He does not know her name to be Katie as that is the name she created when she came to town. He is married to Erin.
Suggested correction: He says "I miss you, baby" and then "I miss you so much, baby."
Character mistake: Stallone says he knows they are in the Northern hemisphere because of the way the water goes down the toilet. The Coriolis effect has no impact on water in the toilet.
Character mistake: The Sheriff calls for Drayton Sawyer to bring out his son Jed (Leather Face) in the movie's opening scene. But it's long been established that they're brothers.
Suggested correction: This is meant to be a direct sequel to the original film, and ignores the other sequels. And if memory serves correctly, the first movie never made any mention of them being brothers. (I just checked and the Texas Chainsaw fandom Wiki backs this up - the original film makes no reference to them being brothers.) So therefore, it is not a mistake if this movie re-writes him as being Leatherface's father.
Character mistake: When Joe and Marie are going over files in the old school, Joe finds a staff letter announcing the enrollment of Amanda Pryce. The top of the letter is dated 1984. However, Joe then proceeds to ask Marie to search for Amanda's file, and tells her to search for the year 1986.
Suggested correction: It's possible the incident happened up to 2 years after her enrollment (starting as a freshmen and the incident being when she was a sophomore or junior).