In Man of Steel we are introduced to an alien ship that has been trapped under ice thousands of years ago. In Suicide Squad we are introduced to a brother and sister who were treated as Gods thousands of years ago. In Justice League it seems that thousands of years ago forces of Atlantis, Themyscria, and Man fought Darkseid's forces....resulting in supposedly 3 Mother Boxes left behind which will be a plot point in Justice League. Only thing is, no one talks about the fourth mother box. Four you say? But I read on other sites it is three. The Fourth Mother Box is actually seen in the deleted scene between Lex and Steppenwolf in Dawn of Justice. Which really begs the question....how did that fourth box get on the ship and how did Lex know about it? It adds to the question of why did Lex want Superman dead so much?
Simple? That talked about fight in the beginning of Justice League involved a Kryptonian. If you noticed at the end of Dawn of Justice Lex in his ramblings talk God is dead and he is coming. Could it be that Darkseid fears the power of Kryptonians and most likely due to a past encounter with a Kryptonian under a yellow sun? Could this Kryptonian be the one from the open pod? I know folks are going to comment "no its Supergirl because of the tie-in comic". Well I say where is she? I have been reading comics and following comic book movies since 1981 and there are plenty of instances where the tie-in is not canon. Where sequels and what not basically pitch the tie in stuff in the trash....IE see Force Awakens or pre-Empire Strikes Back tie ins. I think that open pod is a Kryptonian that will be involved in the ancient battle taking place in Justice League.
In Suicide Squad, Enchantress and her brother alude to their God like status thousands of years ago. But since then until World War 1, there seems to be 0 people with extraordinary abilities. Who defeated Enchantress and her brother keeping them locked away until June Moon finds them? The fact that again this movie has ties to ancient times, like Man of Steel, Justice League to a period of close to 10,000 years ago seems too much to be coincedence.
In Wonder Woman, we meet Dr. Poison. In her early scenes she is appearing to wear a Parademon mask as a hat. True, it doesn't appear exactly the same as the the Parademon's seen in Dawn of Justice, but the green hood and gold goggles are clear homages to the parademons in comics and cartoons. With the actress slated to appear in more movies, people are wondering how? Also, Dr. Poison has the giggle of Mad Harriet, just an odd observation from me and I accept that part is a stretch in my theory. What do we know about the Fourth World? Not everyone is insanely powerful in fact if you read early Fourth World stuff, there are a ton of mad scientists...which fits Doctor Poison to a tee.
And Lex to a tee. What if he was working for Darkseid as is/was Doctor Poison. And Darkseid's finger is involved in every facet of the DCEU. he may not be hear, but it is certainly a possiblity he has agents on Earth, just like in the Comic Books where Darkseid was preceded by Intergang. What if for Darkseid's Elite to come back to Earth, he was biding his time to wait for no more Kryptonians? Lex first tried to have Batman kill Superman, when that failed he had Doomsday do it. He had zero fear over what Doomsday would do to the Earth had Superman not kill him. Thats because he knew back up was on the way the whole time.