There are a lot of really neat ideas that never made it into Big Hero 6, including Rocket Cat and Honey Lemon as a superhero catgirl. And one proposed iteration of the film has a The Warriors feel to it, with gangs whose members dressed like ninja baseball players and shark-mouthed airplanes.
Artist Kevin Dart has shared some of the concepts for San Fransokyo's street gangs that he made during Big Hero 6's production. Among his ideas were the baseball ninjas above, these roller skating geisha:
And these weirdos:
Dart has also shared many other pieces of his production art, including adorable alternate designs for Baymax:
And some Victorian and 1950s Tetsujin-inspired would-be robot denizens of San Fransokyo who didn't make it into the film:
You can check out more of Dart's artwork, including more Big Hero 6 concept art, at his blog.