Gilgamesh's constant self-glorifying refers to the actual Epic of Gilgamesh, which dedicates entire verses every few chapters to praising its hero.
Tomokazu Seki (Gilgamesh) personally thinks Gilgamesh is one of his most frightening characters, and confesses even he is scared of him.
Some locations in Fuyuki City are based on real-life places in Kobe and Fujisawa City.
Series creator Kinoko Nasu had originally planned for Saber to be a male, as befits King Arthur's legend, but he decided a female version would make a more interesting character.