Batman V Superman: 10 Mistakes It Made That Justice League Must Avoid
5. Adding Unnecessary, Boring Subplots
Most people who took their seats to watch Batman v Superman probably expected more than eight minutes of Batman v Superman. Sadly, that's all we got, and that was in large part to a number of extraneous subplots that could have easily been worked out of the film.
The biggest of these was Lois' mission surrounding the mysterious bullet, and it's quite hard to see why this was included when it didn't impact the larger story in any meaningful way.
Every time the film built up some momentum, this subplot bounded in like a leech, sucking the life out of proceedings. Instead of focusing on the main reasons people were excited to see the film - Batman and Superman - Snyder chose to devote time to this plot point which went... nowhere. It was a baffling choice. Lois' wild goose chase felt like it belonged in an indie drama, not in a huge comic-book blockbuster.
Justice League simply can't afford a similar error - it's got a lot more characters to service than Batman v Superman does, so every single second of screen time is precious. It has to meet audience expectations, too - audiences are buying their tickets for the Justice League, so give us plenty of the Justice League!