A classic case of cultural mix in is the use of "OK". That term comes from a country club in Kinderhook NewYork that several of the first presidents belonged too. The club was called Old Kinderhook, and you were OK or cool if you were a part of it. Therefore any film wishing to accurately portray some event previouse to the 1700s should not use that term.

Actually, the origins of the term "Ok" is still contentious and not definitive. It's like the origins of a certain F word in English. Everyone has an opinion about where it came from, but no one is certain.