From the Cover to the Big Screen
This Easter egg is quite obvious, yet the average moviegoer won’t realize it is an Easter egg at first glance. Slight spoiler alert ahead, but there are multiple instances where Joker’s tuxedo and Harley Quinn’s traditional costume can be seen throughout the movie, but the most obvious one comes in the form of a flashback.
When the Joker turned doctor Harleen Quinzel into the Harley Quinn we know and love, there is a small scene that features the two playfully dancing around, which is a direct nod to the cover art of Batman: Harley Quinn as illustrated by Alex Ross. Harley’s costume makes an appearance once more when she’s enlisted in Task Force X and is given back her possessions, and the Joker is wearing that very same tuxedo in a scene near the end of the movie.