At first i was like... isnt this too trivial to discuss? But then i realised that it would be a great opportunity to do a cameo for one of Batman's rogues. Someone Batman could tackle at the beginning (supposedly as his routine) and the movie can begin with the main plot and villain. So congratulations my friend, its a great idea.
Of course, what Rachel Dawes is suggesting isnt bad either:
We didnt see Batman take on low level criminals in TDK or BB. Only in the viral campaigns did we see, well... read in the Gotham Times that batman had stopped a mugging, or pulled a woman out of a car out of control and things like that. And to be honest, we need to see him do that. Its his routine, part of his patrol, and we have only seen him take on the big fish so far.
I am in favour of both suggestions and cant scrap one or the other. So what i am proposing, is that we see Batman take on one of his rogues at the beginning, saving the day when the police couldnt (with the police still chasing him of course) and later on, during the movie, we see Batman on patrol stopping a mugging. Then i dunno, he hears on the radio that the main villain had done something so he rushes there and the plot moves on.
Now, i think that they cant use the Scarecrow again (overkill), and the Mad Hatter would feel odd without any explanation. But Firefly needs none of that. He is a pyromaniac in a suit (if he has a deeper story i dont know it nor do i think its necessary). The police cant stop him and batman comes in and takes him down in a flameproof suit (mouth covered, etc). Then the story moves on....
And its a great way to showcase that batman has many suits for many occasions. I hope that the cave has a huge room full of them, so that would justify why he needs so many.