2x17 Excalibur

By far the best part of the Excalibur arc is Kazuto setting up Agil's/Gilbert's cafe in the virtual world for Yui to interact with. It's strange watching SAO in 2017 where augmented reality is already a thing, and it's no simple task for Kazuto and his friends to merely pull out their phones and see Yui flying around the world in a shared AR space. This is sort of the premise of the SAO movie Ordinal Scale and the SAO spinoff Accel World, but the fact is, this episode takes place in the year 2025 as stated by Kazuto, and that's 8 years from now, and in 2025, they don't have AR yet, creating an anachronism.

Also, anyone who knows anything about Arthurian legend (as in King Arthur, who pulled the sword Excalibur from its stone to become king) knows that Excalibur has never been called Caliber. SAO author Reki Kawahara simply pulled that out of the air. For Suguha to state that the sword has never been called Excalibur just makes the whole thing look bad, considering it's factually wrong. Perhaps it's a poor translation to English, but surely someone at Aniplex (the American studio which translated SAO to English) should have caught that somewhere along the way. Also, I hate how they imply but stop short of saying that Kirito must have "exceptional caliber" to be able to wield Excalibur. Not to mention how Excalibur has nothing to do with the Norse gods, or how aside from Kirito getting Excalibur and Klein getting Mjölnir, nobody got a single reward (that was shown) despite the victory being a team effort. To top it all off, unlike the Fairy Dance and Gun Gale Online arcs, Excalibur really added nothing of value to Sword Art Online. It just gave Kirito a cool golden sword, but his two swords were already impressive. It's a shame Sinon didn't get the bow she wanted. Or maybe Asuna could have gotten the cool golden sword. Or something could have been done to make Silica or Lisbeth relevant beyond being eye candy.