1. How did the Joker get the explosives into MCU? There are explanations as to how he got the explosives in the other places if he spent a year planning his scheme. However, I would imagine that a police station would be difficult.
2. The bat-signal is meant to let people know he's out there, according to gGordon. so how does Batman know he is actually being called to the rooftop, to, say, meet with Gordon and Dent?