Was this a trick?

So Batman, Nightwing, Red hood, Red Robin, and Robin were told Joker was threating to blow up Gotham city when they get there they all hide waiting for the right moment but Joker knew Batman was there so he came out and with Damian he was on a sky scraper waiting when suddenly Harley comes out of now where and beats him and held him over the edge of the building, When he started falling Batman and the others didn't catch him it was......