Kenshin forgot to tell his Master where the Aoiya was (like he couldn't follow the swath of destruction and find it... -ed.).
Oniwaban member: Why do old goats like that live so long? (referring to Saizsuchi)
Okina: Because they know exactly where they're going when they die.
Yahiko: Even if a monster appears, even if the world comes to an end, I will keep my promise to Kenshin!
Seijuro: Fuji, there are some opponents you can't beat even if you use all your strength. One of those opponents is standing right in front of you.
Shisho: The strong survive, the weak die. That is the way I taught him. Can you find a way to defeat him Battousai?
Yahiko: You didn't have to arrive at the last minute just because it makes you look cool!
Seijurou: Blame my idiot student. He forgot to give me directions.
The full title of this episode is The Giant Versus Superman: Like an Arrow Shot at a Time of Despair.
There is a particular reason Iwanbo up and runs away, as he is a spy for a future Kenshin opponent, Enishi Yukishiro. Iwanbo is, in fact, a finely constructed suit, controlled by a puppeteer. Unfortunately, as the manga had not resolved that storyline before the animators began producing season three, the writers created original stories that were of such low quality, interest in the series waned to nothing and the third and final arc in the manga was never animated.
Hiko Seijurou ends the assault on the Aoiya by defeating Fuji with the Kuzu Ryu Sen.
When in his armor and headgear, Fuji looks vaguely like EVA-01. Coincidence?
In the event of a double-cross on Shishio's part, Kenshin asked his master Hiko Seijurou to go to the Aoiya and protect Kaoru.