If You Missed Man Bat's Halloween Easter Egg In Batman: Arkham Knight...

Don't worry.

This Easter Egg is a special timed secret - appearing only when you play the game on Halloween. If you'd like to see it anyway, simply set the console or PC's internal clock to October 31st, and start up the
game. After you have completed the Creature of the Night side quest in Gotham's Most
Wanted, start using the grapnel boost off of large buildings (most of the ones in Miagani Island will suffice) and you'll be surprised by the re-appearance of a previously defeated villain. You can head back to the GCPD to find out about what happened
to the villain's containment as well.

Spoiler Link - Easter Eggs and References - Batman Arkham Knight Wiki Guide - IGN

:)

 

Lots of Easter eggs

I played the game Batman Arkham City and it had varietys of different easter eggs it was cool having to discover them, But the scarecrow easter egg is a little creepy

the one with with the cryptographic secquencer.

If you read this please leave a message or a comment.

 

Batman: Arkham Knight

I loved the riddler puzzles in arkham city the cyptic ones that took you too a batman easter egg but the first thing I do is goto crime alley to pay my respects