1) No Green Lantern (Hal Jordan)
Yes, the absence of Green Lantern from Justice League’s line-up was extremely obvious to fans; however, it affected the story a bit more than you might think. In the 6-issue New 52 run (also known as Justice League: Origin), Hal Jordan is almost the centerpiece of the ensemble. He’s the second member who arrives to investigate the rash of Parademons in Gotham City and becomes the driving force in discovering the oncoming invasion.
In Justice League, the Parademons arrive on Earth the same way they do in Origin, but in the comics, Green Lantern stumbles upon Batman when he comes across the first one. From their initial interaction, Green Lantern and Batman become fixtures in the story, with Hal Jordan being the comic relief in the face of tremendous danger. Lantern’s absence also causes Justice League to make several alterations to the source material throughout the film, but it mostly resulted in a power vacuum in the team dynamic.
Throughout Justice League: Origin, Green Lantern’s arrogance leads to mistakes when confronting Darkseid, but his resolve to correct those errors ultimately causes the team to unify. Without the character in the film, the weight of his role fell upon Batman and Wonder Woman, which worked out fine, but at the same time, the group felt incomplete and a bit outgunned.