What missable dialogue, loot, areas have you encountered.

I have a few.(very minor spoilers)

-Entering 0451 in the first keypad of the game will give you an achievement/trophy.

-Giving a neuropozyne to a guy with a shaved patched in his head in prague (can't remember where exactly) will get you access to his basement where you can get a card that can get you into a vault in the bank where you can find really good loot.

Can't remember anything else, will update later. Just an advice. The bank and TF29 base has the best loot in the game, everyone should explore them.