How did the Joker survive the helicopter crash in Suicide Squad after he pushed Harley Quinn out of the helicopter? The crash seemed impossible to survive from.
One theory that's been floated in various circles on the internet, but neither confirmed nor denied by the makers of the movie, is that Joker's survival might have been the result of Harley Quinn's deal with Enchantress (script lifted from here).
HARLEY: Hey lady? I lost my Puddin'. But you can get him back, right?
ENCHANTRESS: I can, my dear. Anything you want.
HARLEY: You promise?
ENCHANTRESS: Yes, child. You need only Bow ... and serve beneath my feet.
Of course, shortly after that, Harley betrays Enchantress, but there's a chance that Enchantress had already fulfilled her part of the deal, restoring Joker to life.
During the helicopter crash scene when Harley Quinn falls on the building, the scene remains there and we see Harley Quinn's somersault for a few seconds and then switch back to the crashing helicopter.
Maybe during that time Joker also jumped from the helicopter to some safe place before the helicopter crashed. And rememberer that Joker is a famous escape artist and great surviver in the comics too.
One possibility that nobody mentioned yet is that the Joker planned all along to stage his own death.
This can explain why he pushed Harley Quinn out, on purpose:
I think it was in order for him to be able to stage his death, without Quinn interrupting, while knowing she'll survive, as it was right above a building.