Maybe you see a plant you have to collect in game or a rock wall that looks different. What items have you caught out of the corner of your eye that you realized was just your brain so focused on looking for things in a game that you saw it IRL and made you double take?
Back when I was playing a bunch of Oblivion, I was doing the quest to find Nirnroot (Seeking Your Roots). I was spending so much time looking for them I started seeing them in real life out of the corner of my eye everywhere (it was usually actually thistle). I’d have to stop and look because I knew it was important, before my brain would kick in and I’d realize that it was from Oblivion.