1. The "More About the One Year War" shorts that used to come with the 08th MS Team tapes, which you can find in the Blu-Rays (can't post links, sorry. If there's anyone who wants to see, ask Zeonista by PM. He's got a link).
2. Statements from people about plot points, like how Seiji Mizushima stated that E.A. Ray meant "Eternal Alan Ray."
3. The Ring of Gundam short, which goes like this:
Source: http://www.zeonic-republic.net/?p=698
This story borders on the Universal Century.
The Earth Federation Forces which was eradicated in the ancient times is reborn, having revived primary industries from development to construction. Through the Earth’s natural environment and solar energy, they were gradually able to focus on military forces.
The military forces were maintained because an invasion from “EX”, the last space colony full of war criminals, was foreseen.
And another reason why was a battle for the ring colony.
The foundation of the ring colony was bedded with nanorobots and over these several hundreds of years; it grew into a ring shape more than five-hundred kilometers in diameter. These were the historic ruins of the Universal Century and this monolith was no match for past space colonies.
During such times, a “beauty memory”, that which was a symbol for all of mankind’s memories during the last century, was discovered on a mountain on Earth. It was protected by an iron-like rock that could not be opened on Earth.
Captain Glenn and AG of the “Skull Unit” venture into geosynchronous orbit via a space elevator to where the battleship “Tatsu no Otoshiko” (Seahorse) is moored. They rush toward the ring colony because he heard from the memory about the “Legacy of Amuro”.
The stationed troops of the AX had already entered and the ring colony was included in the restoration of the “Legacy of Amuro.” Captain Glenn and the others of the “Skull Unit” take off from the “Seahorse” and infiltrate the colony. Although they encounter the legacy of Amuro, When AG tries to hijack the First Gundam when he sees it as it is, one of EX’s lifeguards, Yuria, tries to stop him.
However, the two board the operational Gundam and exterminate Glenn’s “Skull Force” and return to the ship. AG was a spy dispatched from the EX. He slipped into the Earth Federation Forces in order to search for the “beauty memory”.
The memory, housed on the “Seahorse”, responded to the Gundam. The mass of excavated rock was the memory. It was able to search for itself with the data resonating within the Gundam. When seeing the behavior of the rocks and the Gundam, the mobile suits of the “Skull Unit” had no choice but to watch.
When the rock the Gundam touched was broken, a memory capsule appeared, in it the form of a sleeping “beauty memory.” And, she spoke.
“Man can someday link with the legacy of Amuro and send all of Earth’s memories to the new Earth.” However, the “Beauty Memories” were handed down from generation to generation. It’s said that the Ring Colony was a “ship” to sail to a younger solar system beyond our own.
“Even if the sun were to perish, man can still live on. Because, the capacity of the ship is infinite… its aim is infinite… but it does not aim at God. The repetition of life is something that coexists with the infinite universe. Moreover, the challenge is a duty that was imposed upon life. To be good to one another… Otherwise, destroying oneself is an assured life.”
However, Captain Glenn and the “Skull Unit” fear that the Ring Colony would become the EX’s advance base for attempted supremacy over Earth, so they try to destroy it. AG and Yuria try with the little battle strength they have to stop them. Because of the amazing mobility of the Gundam that has the legacy of Amuro in it they exterminate them and finally are able to attack the Earth-side base of the “Skull Unit.”
Meanwhile, the ring colony approaches the space elevators orbit and is exchanged with the weight balance.
It is work for breaking away from the solar system.
People believed that it became something to be able to send the mark of human presence in the ring colony which housed both the Earth Federation Forces base and the “Skull Unit” base inside it, to the new Earth.
AG and Yuria are able to come in contact with such people and come to understand the miserable history of mankind that the “Beauty Memory” speaks of. Because of this, it is possible to exterminate the “Skull Unit” that has run out of control. AG and Yuria could then return to the Ring Colony using the space elevator.