I don't think "anachronism" is highfalutin because I don't know any SIMPLER way to say it.
The Internet Movie Database, imdb.com, is essentially a popular culture site, not a cineaste's site. For every movie, imdb.com has a list of "goofs." Not "errata" (highfalutin), not "mistakes" (plain English), but "goofs" (colloquial). They are not trying to be pretentious or highfalutin.
Movies set in historical times will usually have errors like the one spotted in "Robin Hood, Prince of Thieves:" "Azeem is shown using a refracting telescope, which was not invented until the 17th century."
imdb.com calls this kind of goof an "anachronisms."
What else COULD you call them? m-w.com shows me many rhymes, but no synonyms. Their definition is "a person or a thing that is chronologically out of place." That's four times as long as "anachronism," and uses a 15-letter Greek-derived word to define an 11-letter Greek-derived word.
"Anachronism" isn't a simple word, but what else could imdb say would do the job? "History goof?" "Century fail?" "Scrambled time?" "Persons or things that are chronologically out of place?"