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?
When I play a lot of Rainbow 6 Siege I have the urge to shoot out security cameras IRL
I did that when playing Splinter Cell. That, and looking for pipes to climb.