Over at the Smithsonian's Natural History Museum, one of their exhibits has been erroneously referring to the Precambrian period as an "era" rather than a "supereon." It took 27 years for someone to notice, and that someone happened to be a fifth-grader.
If you listen to the piece, you learn that the Smithsonian acknowledged and corrected the gaffe (yay!), but sent their thanks to the wrong city and misspelled the kid's name (boo.).