Nobody doubts that Justice League was always going to be a long film. Besides expanding on the stories of Batman, Wonder Woman, and Superman, it also introduces Aquaman, Cyborg, and Flash, so plenty of time needs to be spent on those three characters alone. Plus, the trailer revealed scenes that looked epic in nature (Lord of the Rings kind of epic), which means that the flashback sequences (that fight between Darkseid's forces and the Earthlings) will be quite lengthy.
However, Justice League is even bigger than we expected, in the sense that it will be even longer than Batman v Superman: Dawn of Justice. According to IMDB, Justice League is 170 minutes long, or ten minutes shy of three hours. And this could be a problem, especially for those who weren’t sold by the trailer, or those who were disappointed by prior DCEU offerings.
There is an art exhibition for DC Comic films @ArtLudique, here’s some JL concept art. pic.twitter.com/zCwftctNA3
"” Seán Murphy (@ReelFada) March 29, 2017
Considering his previous work (Watchmen), this is without a doubt a Zack Snyder movie. However, since this is an IMDB update (and IMDB may not be reliable from this point of view), the runtime could change. If test screenings don't fill Warner Bros. with confidence, a good portion of the movie could end up on the cutting room floor.
Once again, that would be a very Zack Snyder thing. After all, huge chunks were cut from Batman v Superman: Dawn of Justice, and some of those were added to the Director's Cut home release.
If this runtime proves to be accurate, Justice League will break at least one record, as the longest superhero movie from any shared universe. It's even longer than Christopher Nolan's epic finale to The Dark Knight Trilogy, which ran 165 minutes.
But, hey! At least there’s time to reintroduce Superman; spend time with Wonder Woman and Batman; start the stories of Aquaman, Cyborg, and Flash; present a history of the Mother Boxes on Earth; introduce the New Gods; make Steppenwolf a worthy villain; and (who knows) have the heroes eat shawarma afterward. And, after all of this, there'll still be time for a Green Lantern cameo.