Being an introduction into the Singularity (and considering the limited options for Ritsuka/Mash), it is understandable that they won't be dishing this out just yet. While they made the effort of fending off the Uridimmu, the stage was primarily set to show off the powers of an (unnamed) Ishtar and the man who introduces himself as "Enkidu"—with them ripping apart the beasts with little to no effort.
Merlin's introduction (together with Ana), which allows them to disabuse Ritsuka and Mash of "Enkidu's" ploy and then engage him quickly. Enkidu was by no means inconvenienced by this, fighting them on superior terms—which then forces Merlin to teleport them away.
The episode also ends with their introduction to King Gilgamesh—who wastes no time in declaring he will test them personally with his Gate of Babylon. Quite a significant shift in his very petty incarnation (especially as he appeared in the Zero / stay night timeline).
The opening battle itself is quite tense, with Gilgamesh's onslaught on Ritsuka and Mash (plus a very reluctant Ana) subsequently complicated by the arrival of Ishtar. And while Gilgamesh managed to prevent Ishtar from using more powerful spells, even she almost had Gilgamesh dead to rights with a shot—until Mashu deflected it just at the right moment. Immediately after this, Gilgamesh goes back to overseeing reports like nothing happened, even dismissing everyone at court without a fuss (at least frontally).
Note as well Gilgamesh's demeanor throughout the entire proceedings: none of his actions were done out of caprice, haughtiness or pettiness. Even when Merlin implies Gilgamesh's dismissal of Chaldea is due to his pride, he very quickly shuts it down by pointing out that he doesn't feel like they're an asset to him because they haven't demonstrated that they care enough about Uruk yet.
Episode 4: Jaguarman utterly thrashes Mash and Ana with playful ease after they underestimate the threat she posed because of how silly she is. Her speed and power let her juggle her opponents in the air and smash through their guards while providing no opportunity for a counterattack, showing the ferocity of a true warrior god.
Episode 5: Gilgamesh opens the largest Gate of Babylon yet seen in a Fate animenote though not the largest one period; the one seen in his fight with Enkidu in the Fate/strange fake manga was even bigger. to counter the fake Enkidu's Age of Babylon.
The battle between Gilgamesh and fake Enkidu itself deserves enough mention. Despite being comparatively low-powered (especially considering the titanic fights these two have had), you see the weight of this confrontation on both their faces ("Enkidu" trying his damndest to ignore his clouded memories, Gilgamesh striving to not betray his troubled thoughts). It's telling that among the different kinds of Adaptation Deviation done by the anime, this one is among the most well-received.
Episode 8: Ushiwakamaru and Leonidas hold off Gorgon's assault with their Noble Phantasms. This is especially notable because both characters use old, basic animations in the game, so this is our first time seeing their Noble Phantasms as the creators might have actually imagined them. Leonidas also gets a Did You Just Flip Off Cthulhu? moment as he smack-talks Gorgon while dying.
Gorgon for her part, made it perfectly clear, with her many laser-shootingsnake heads, that getting close enough to land a blow is easier said than done. Nevermind the fact that she was fighting Ushiwakamaru with a giant hole in her torso.
"Ziusu-dra" shows up completely out of nowhere and severs the magical contract binding Ereshkigal to the Three Goddess Alliance. Bear in mind that severing a magical contract requires a certain kind of anti-magic weapon or ability, such as Medea's Rule Breaker. We're not told of him ever possessing such a thing, and yet he does it anyway. It's enough to make you wonder who he really is...
A small one, but remember when Gilgamesh laughed his head off at Fujimaru for suggesting that Chaldea would defeat the Three Goddess Alliance? Well, with both Quetzalcoatl and Ereshkigal joining them to fight against Gorgon, the Three Goddess Alliance has technically been "defeated". Looks like Fujimaru kept his word.
Quetzalcoatl and Kingu's fight, with both opponents fighting each other on more-or-less equal terms.
In a somber moment right before the battle against Gorgon begin, with the ending song "Prover" playing in the background, Ana reveals her true identity as she unseals her Divinity and activates her Mystic Eyes of Petrification. It's Medusa vs Medusa.