Batman: Arkham Knight features some very cool jump scares. I lost track of the times I was grappling around Gotham City, only to have The Joker or Man-Bat suddenly leap out at me from a rooftop! As it turns out, even after completing the game, it will still happen...but only on Halloween. Set your console's clock to October 31st and start up the game, and providing you've completed the "Creature of the Night" side quest, Man-Bat will make a surprise reappearance!
More details are in the video below, and if you head to the GCPD once this happens, you'll find out how exactly he escaped captivity. What were your favourite Batman: Arkham Knight Easter Eggs?