Hm, could the Panty + Brief Ep have happened yet?
I keep having a thought that there's some sort of flashback to that. Perhaps at the final fight where Corset and Garter are fighting, and Shinji interrupts.
Now there's no way Shinji would survive direct combat with Corset. Not unless he had an overwhelming or surprise attack that took him out immediately. Well my mind flashed back to the part:
Chuck teaches Shinji how to drive.
And there just so happens to be one Angelic 'weapon' that isn't at the battle in that episode. See Through.
Shinji crashes the battle with the Holy Humvee, possibly loaded with every weapon Garterbelt has in the back seats. Prepped entirely for war, it's all for moot when he accidentally CarFu's Corset off the side of the building on arrival, and barely misses Garter.
Course that changes the whole dynamic of the ending, now Panty and Stocking don't have Garter's black card. So they instead maybe they have to try and get Brief out of the lock.
Ah well this is entirely superfluous to the so far discussed plot. I just thought it's be cool/funny.