Norris Packard single-handedly holding off the entire 08th MS Team and their reinforcements to protect a hospital ship, thus showing just how dangerous an Ace Pilot is compared to "normal" soldiers. Here it is, in all its glory.
Shiro himself gets a minor one during this fight after going into something of an Unstoppable Rage by ripping off his own mecha's arm and bludgeoning Norris' mecha in the face with it. Fun to watch, but would have been significantly more awesome if he had thought to use his beam saber instead, which he still had (and in fact uses later in the battle).
Packard: "That's right! Cower! Be afraid! Die knowing you lost to someone who truly knows how to use a Mobile Suit!"
Alternatively, props to the grunts of the 08th for managing to take down the sort of person who normally kills them by the dozen in regular Gundam shows.
Arguable since, while it is significant for them to have won Norris used his final attack not to finish off the Gundam, but the Guntank and in doing so complete his goal rather than simply prolonging the fight.
These moments pale, however, when compared to the first episode, in which Shiro destroys a high-mobility prototype Zaku(which is essentially a Rick Dom with a Zaku torso and head) with a Ball.
When Terry's Gundam jumps to attack the first Apsalus encountered by the protagonists, can basically be summed up as "Real Robot, that's a Gundam! I can die happy!"
The Magella Tank team holding off of the 08th Team. Looks a bit mundane, if not for the fact that they held off two Gundams with three tanks, and this is long after it has been established that the Magella Tank has it tough against even GMs.
Lt. Col. Kojima turning on Ethan Ryer and arresting him, demonstrating that even in a war as brutal as the OYW, and a society as corrupt as the Federation has a reputation for being, there are still people who are willing to stand up for morality and doing the right thing.