In the suicide squad trailer you see two men wearing masks one a goat and the other is wearing an eyeball mask
And then you see them putting Harley Quinn on a surgery bed
I'm sry the eyeball mask is a bad screenshot but getting to the point u see them firing and then there r a bunch of scenes and then we see right after that goat face seen we see someone putting Harley Quinn on a bed like a surgery bed maybe one of the gang?
and in most of her scenes harley quinn is the joker's doctor (before transformation) And that bed looks exactly like the bed from the end of the trailer Where the joker makes Harley Quinn transform to crazy which means (based on before theories )
This gang is working for the joker and they were escaping him from arkham asylum. And then he transformed Harley Quinn crazy!!