In 2009, I published a little book (in Dutch) in which I discuss more than fifty common errors about ancient history, Spijkers op laag water. Below are some examples, a couple of which are absent from the book. I have presented my subject matter in a sequence that allows the reader to read the book as a narrative history of Antiquity too, albeit a narrative history with some unusual digressions.
Listed are 27 errors. Lots of good stuff, including the Legio VIIII Hispana discussed earlier (#22).
There is a related page, Ancient History and Pseudoscholarship.