Given the fact that any language used in such a movie is going to be wildly unlike the language spoken in the time and place of the movie, I think that's a mild anachronism
i usually complain to the wife when horrible tactics are used in medieval battles.
like... why is everyone always doing a full frontal assault, have the wrong weapons, not use fire appropriately, never flank, use cavalry inappropriately.....
Something I dislike in movies is when a movie is set in a non-English-speaking country, but all the characters are speaking English. I would rather have the characters speak the proper language for the country, with English subtitles. But I guess the movie execs have calculated that subtitles will make the movie less profitable.
Often times, I think of movies or stories as the story teller as translating for the audience. You don't watch Troy and think it's odd the characters are speaking English.
It's acceptable to complain if the work is nonfiction and meant to be for education.
Archers also didn't usually shoot upwards to arc their shots. It loses power, reduces accuracy, and makes it more likely for them to hit armor, not less.
Using modern english phrases to convey meaning to modern audiences is usually fine to me, as long as they don't reference modern history or events. but what really pisses me off is movies like "The Great Gatsby" that take place during the 1920s and have JayZ and Lana del ray playing at a rich person's party