In seasons 1 and 2, characters repeatedly refer to a singular specific person as being an "alumni" of Nevermore. "Alumni" is plural, referring to multiple graduates. When referring to one specific graduate, the correct terminology is "alumnus" (singular - male) or "alumna" (singular - female).
It is repeatedly implied that Sheriff Galpin answers to Noble Walker, who is the town Mayor of Jericho. This would be true if Galpin was a police chief, but sheriffs do not fall under the jurisdiction of towns or cities. Sheriff is an elected county position. Galpin would not answer to or be under Mayor Walker in any way.
The series regularly uses "Goody" as if it were a name. Goody was never a name. Goody used to be a title, similar to Mrs., that indicated a married woman.
Everyone in the current century talks about Goody Addams as if "Goody" was her first name. While in the 17th century, "Goody" was not a name, but a title used for some women like "Mrs." is today, it is probably not a goof. Addams family relatives were known for having quirky and unusual names, including "Anorexia," "Slimey," and of course "Itt." "Goody" as an actual given name would not be implausible.