Something that totally shocked you learning it or realizing it. I might be using the wrong wording here, but ill give you my example:
In Ocarina of Time, we all know the Triforce was cut, or otherwise not something you get in the game, save for in the cutscenes towards the end. BUT - did you know you can actually go find it and see it in the game?
If you have a Gameshark, turn on the levitation code. Go go Zeldas Cortyard in the room where she is, and fly over the wall. When you fall, you’ll land in a pool of invisible water, and underneath the center of the room with the flowers, look down - there it is. Can’t interact with it, but you can see it, and i choose to believe putting it in that exact spot was intentional for lore reasons.
What do you got?
My favorite is probably anything from TES. Explaining CHIM or mantling or even breaking down this diagram
The whole idea of the Dragon Break/Warp in the West is one of my favorite pieces of game nonsense ever. Yes, all 7 endings of Daggerfall are simultaneously canon, because Akatosh got really drunk and so 7 different people all simultaneously obtained control of an artificial god and proceeded to do god things with it. Time just didn’t exist for a while, don’t worry about it.
Also it created a new god out of the super powerful emperor from a few centuries ago (except now he’s retroactively always been a god), don’t think about it.
My favourite is how one of the Sermons of Vivec is about Pokemon.