Classicist David Larsen (UC Extension) has a piece on the year in classical cinema:

THE "sword-and-sandals" film comes in three generic flavors: barbarian, biblical, and Greco-Roman, each envisioning the martial values of a bygone "time before gunpowder" in its own fashion.

While the first category may be counted on to support a heavy admixture of sorcery and fabulous monsters, the prevailing conceit in the biblical and Greco-Roman epics is one of historical realism. Costumes and manners are based on the soundest classical scholarship Hollywood can buy, and intelligible modern motives are supplied for the most outlandish deeds of history and legend.

It's a short and entertaining read.