Revealing mistake: In the scene where Themistocles first talks to Queen Gorgo, in the background you can see several extras, one of which is wearing obvious sneakers. (00:18:35)
Revealing mistake: When Chris and a companion are on a rooftop in the midst of clothes lines with sheets hanging to dry, all the sheets have creases indicating they had been recently unfolded or removed from original packaging before being hung on the lines.
Revealing mistake: Most of the tank battle scenes throughout the movie are low budget CGI.