Shirou trolling Gilgamesh with video game spoilers.
To elaborate: Gilgamesh is playing Final Fantasy VII. As he enters the City of the Ancients, Shirou informs him of Aeris (whom Gil named Saber) getting killed. Gilgamesh thinks he can just revive her, but after being told he can't: "STUPID GAMEPLAY AND STORY SEGREGATION!" And Shirou does the same gag a couple of chapters later, this time spoiling the first visit to the Northern Crater.