In Battlefield games when you interrupt the reload process and go back to reloading, you will start where you left off. I can't believe more games don't do this. The devs also go out of their way to fix things as simple as the gun looking wrong when reloading. Some gun enthusiast YouTuber made a video at how some lever on some rifle was 12 degrees off and they actually included a fix in an update. For something you're able to see for only two seconds.
You can chuck in all of Uncharted into this thread. The way that conversations continue after being interrupted, the characters' animations, that one time you tied a rope around a tree in a realistic fashion.
The Arkham games have a lot of fun little details too. In Arkham City, when you first fight the Joker, who turned out to be Clayface, if you use detective vision you will see that his character model is solid and doesn't have a skeleton. In Arkham Knight the city would change to reflect Joker's virus in your mind, sometimes in such subtle ways that you wouldn't notice. Also, if you throw a remote Batarang at yourself, you will catch it. Taking it to another level, if you throw one at an ally (and this would happen essentially only in a combat encounter) that ally will catch it. There's a shit ton of more little details in it, enough so to make hour long videos about easter eggs in a single game.
EDIT: God, more and more keeps coming to me. In Battlefield, if you kill a person in the grenade throwing animation he will drop that grenade and the grenade will kill his team mates. In Battlefield 4, you can actually shoot down cruise missiles. They actually went and made a damage model for an object moving at hundreds of miles per hour because they thought some players could shoot it. And they did. In Battlefield 1, mud and rain cover your gun as well as the player. Just watch and Mythbusters from Defend the House on YouTube. From Battlefield, CoD, and other multiplayer games, they have it all.
The OP said he's playing MGSV right now (so am I, pls don't raid my FOB). I won't spoil anything, but there are some "secret" things to know that actually makes playing the game better. For one, you can knock down electrical posts that will cut out electricity to the outposts its connected to. The wires from these posts can actually kill people. You can also knock out soldiers by throwing a magazine at their heads. If you shoot a guy with a helmet in the face, he will still die. Obvious, I know, but other games would read a shot like that as hitting the helmet. You can knock out soldiers with supply drops (you can beat the first mission with Quiet with the easiest S-rank ever through this). The supply drop flares will actually incapacitate enemy soldiers. They'll just stand there coughing. I found this out completely by accident. I threw a supply grenade thinking it was a sleep grenade. I turned away and looked back just in time to see a supply crate knock out a coughing soldier. If you drop a soldier in shallow water, he will drown. Also, for some reason throwing a guy over the railing of mother base does not count as a kill. And to finish it off, you can make D-Horse shit on the road, causing small vehicles to spin out. And there is so much more than just this.
Sorry for the wall of text, but small details and easter eggs are my kinda thing.