Revealing mistake: When Nathan and Audrey are sitting at the table in The Grey Gull, the extra in the background can be seen bringing a loaded fork inches short of his mouth then fake chewing. This happens a few times before cutting to the ending credits. (00:40:05 - 00:40:55)
Revealing mistake: During the final battle there is a dual between Julius Caesar and Gannicus. At one point Gannicus spins Ceasar around and he is shown to wear modern day underwear.