2. The Man Of Steel Krypton Reference
There are of course a number of signs and billboards in Man Of Steel that hint at the inclusion of future villains and heroes, and the most obscure is probably that of the 'Utopia Casino' that appears in the background, which hints at a supervillain, and which was apparently sneaked in by a crew member, according to Zak Snyder: "...Yeah, well that's John 'D.J.' Des Jardin, my visual effects supervisor. He snuck that in there and I was like, 'That's awesome.'" The casino points towards Tony Gallo, who owned the Utopia, and who was responsible for bringing Superman into contact with Kryptonite for the first time in the comics. Obviously Snyder made an early point of ruling Kryptonite out of Man Of Steel, but it seems that Jardin got a bit of a nod in at least, suggesting that we may see the green stuff in a sequel.