That was probably the drone they mentioned in several articles that Batman was using to take out the criminals without leaving the batcave. Back when Superman Returns came out with Brandon Routh, I kinda swept it aside and didn't watch it as there were a few things which didn't fit the characters that I knew through reading. But, I recently watched it, and I have to admit that Brandon Routh was perfect as Superman. The way Superman is supposed to be on screen. The Hero. Kate Bosworth was okay, not my first pick for the role.
That was Batman's one rule. No killing. And the Joker was trying to push him to break it. He stated something to the effect of Batman being an immovable object. Even in the comics, Batman if I recall never killed, though maybe came close. In Hush, he came close when Selina Kyle had her heart ripped out. Came close when the Joker blew up Wayne Manor and killed Jason Todd. Joker shooting and paralyzing Barbara Gordon. How many times were there that Batman could have killed, but didn't?