Happens twice in the same chapter, when we see what Kyon did to intimidate Mori after the 12 Yakuza. He smashed through a skylight over thirty feet in the air, landed unharmed, made a gratuitous display of telekinesis, handed a spy over to the Organization, and blackmailed her into letting Koizumi become a liaison. He then jumps back out through said skylight.
If Kyon's fight reminisced a soldier in a desperate situation, then Haruhi's was like a savvy player in a new game. She invoked semi-autonomous Pure EnergyAttack Drones, made extensive use of Telekinesis to manipulate enemy fire and the terrain and was able to devise and discard several tactics on the fly while fending off a lot of enemy Synths at the same time. She easily outclassed every Mook in there but she sorely lacked the right mindset to fight.
All the preliminary steps to this moment taken by Achakura are an amazing mix of guile and improvisation: Can't activate Kyon's tools due to the genetic imprinting system? Get his sister to unlock them. Being forbidden of speaking first because of the "good-child mode"? Prompting Nonoko to speak to her first by catching her attention with simple visual signals is not included in the prohibition. Once she got her attention, how to convince her to help without lying? Appeal to what little she knew about the girl by staging the whole thing as a Call to Adventure scene out of a Magical Girl anime (Bonus Points for modeling themes and outfits based on twowell knownseries which she probably picked up from This Very Wiki). Nonoko is too slow to get to Kyon in time by herself? InvokeMega Neko trope on Chekhov's Gunman Shamisen, take a ride on his back while keeping the whole group invisible and directing him through and over traffic. Arguably the best part is that all this took place within the span of minutes.
Kuyou destroying her alternate self with the activation of her chibi-mode. Yes, you read that right. This may require an explanation: Until the moment Kuyou joined the SOS Brigade, she didn't possess the innate capability to retain information. Instead her sentience depended on her enormous observational scope, in both the spatial and temporal sense, to re-observe each event as needed. Knowing this, slider!Kuyou tried to overwhelm Kuyou's awareness with observations of her own alternate reality by "synchronizing" with her, a process which would effectively overwrite Kuyou to the complete likeness of the former. To avoid this, Kuyou activated her previously unused chibi-mode, becoming something practically undetectable to slider!Kuyou's perceptions. The end result was that slider!Kuyou successfully synchronized with an effective "nothing" and basically deleted herself.
The Awesome Art present in the fic's VN is this on its own, but becomes even more impressive with the introduction of Kanae. The creators had, at most, a few pictures from the book to base her off, but their depiction of her was given as much originality and detail as the canon characters.