It's gratifying when a student in my editing class detects an error in the professional media, especially this early in the semester. Here's the example from ESPN.com that someone brought to my attention:
Novak Djokovic's last name is misspelled in the first paragraph; it's correct in the second. Sure, it's not an easy name to spell, but when it appears in successive, similarly structured paragraphs, the difference stands out. It's up to an editor to notice.