Batman: Arkham Knight - 10 Coolest Easter Eggs, Secrets And References Explained

Most players who went through Arkham Knight's story will probably agree that the game's best segment comes during the return to Panessa Studios, where Batman and Robin have to deal with a fake Joker breakout courtesy of Harley Quinn.

There are some truly great moments in the mission, including a lovely little song number from Johnny Charisma (who Batman hallucinates to see Joker), but there's also a sneaky Easter egg fans may have missed.

In order to enter Stage C and apprehend Johnny, players must input a passcode. The code itself is 0539, and if you turn that into a date, it becomes May, 1939 - the month and year Batman made his very first appearance in Detective Comics #27.

Subtle, but a lovely touch all the same.