One of those references, though, might have been planted specifically to set up one of the numerous films currently on DC's development slate.
Gotham City Sirens -- the female-led Bat-family movie planned from Suicide Squad director David Ayer and featuring, among others, Margot Robbie in her role as Harley Quinn -- may have been on Snyder's mind when he planted a nod to Janus Cosmetics.
Janus is a massive cosmetics empire once run by Roman Sionis, the Batman villain known as the Black Mask.
The tease of Black Mask by Ayer coupled with the Janus Cosmetics name drop -- there was a giant, neon Janus sign on the Gotham rooftops where Batman was chasing down a cat burglar and ultimately facing off with a Parademon at the start of the movie -- feel like more than a coincidence, especially after Snyder spent so much of Batman v Superman: Dawn of Justice inserting what seemed like an infinite number of Easter eggs and setting up Justice League as much as he could.
Justice League is in theaters now.