In 2007, Warner Bros. began production on a Justice League movie. This would have preempted the forthcoming announcement of Marvel's Avengers team-up. Fan reaction was loudly against it, especially considering that - at the time - Christopher Nolan's Dark Knight trilogy wasn't even halfway completed, and the idea of a competing Batman character (played by a then-unknown Armie Hammer) seemed disrespectful and boneheaded. The rest of the cast, including G.I. Joe Retaliation's D.J. Cotrona as Superman, inspired similar derision. When the movie collapsed due to a loss of tax breaks just as it was about to start filming in Australia, many breathed a sigh of relief. But the script recently leaked online, and it turns out to be far better than expected. While it probably wouldn't have been as good as Joss Whedon's Avengers, it's a lot better than early reactions claimed. The film, titled Justice League: Mortal, featured an already established Justice League clashing with Maxwell Lord and an army of cyborgs called O.M.A.C.s. So what can Warner Bros. learn from its aborted project? Well, let's delve right in and take a look, shall we? Please note: this post contains spoilers. If you haven't read the screenplay for Justice League: Mortal yet, I advise you do so before reading on...