Fan Casting Post-Credits Scene in Batman Beyond

After some time has passed, the scene shows Terry patrolling Neo-Gotham, until he notices something strange. [Terry] - Oh, Bruce, what's the weirdest thing you've ever seen? [Bruce] - I already told you about that time with the bomb penguins. [Terry] - Well, I think this is definitely weirder than penguins... Before the screen fades to black, the camera points upwards, where a sort of crack can be seen in the sky, before disappearing.