Batman V Superman: 10 Mistakes It Made That Justice League Must Avoid
6. Trying To Catch Up With Marvel
Batman v Superman's overstuffed nature was a clear retort to Marvel's extremely successful cinematic universe. DC and Warner Bros wanted a slice of that comic-book movie pie, and in their haste they tried to cram as much into the film as they possibly could.
Unfortunately, not all of it worked, and if the DCEU is to one day flourish, it needs to respect its characters and universe and take its time rather than trying to exploit them for a quick buck.
Batman v Superman made the mistake of trying to introduce the DCEU's major players, set up future movies, tell a self-contained story and act as a sequel to Man of Steel, all in one go. It was exhaustively overstuffed. Justice League stands a better chance at avoiding a similar fate though as, by that point, Batman v Superman and Wonder Woman will have done the legwork in terms of major character introductions. But the film must nail it.
Marvel have proven that taking your time with the characters pays off (literally), so rather than throwing everything and the kitchen sink at Justice League, DC need to take a step back, take things one movie at a time, and make that one movie great. You don't build a successful universe overnight - you build it over several years, with a number of confident, cohesive films.