Spoilers ahead.
The movie leaves it ambiguous whether Carmine Falcone really had the Waynes killed or not, but just as I hated the idea that the Joker was the killer in the original 1989 Batman, I hate the idea here. To me, it’s really core to the conception of the character that Batman was inspired by a completely random murder by a totally inconsequential street criminal; Batman is a response to a culture of mundane crime and lawlessness, not just a foil for a roster of weird villains. Making the murder of his parents part of a big mob conspiracy or the work of a supervillain confuses the most basic element of the persona.
Why is this movie three hours long? Whyyyyyy?
An easy way to trim a half-hour off would be to take out some of the mob stuff, which is overly complicated and frequently drags.
And for the record, I just don’t think the central “who is the rat?” thing works. You rat to avoid prosecution - you work with the establishment - but Carmine Falcone supposedly rats in a way that allows him to take over the establishment. I have no idea how this works. I get that ratting out another mobster paves the way for Falcone to take over the mob, but the strong implication is that being an informant has given Falcone some power over the police and prosecutors, rather than the other way around. How could being an informant allow you to control the police? It’s unexplained, I suspect because it’s unexplainable. But that “who’s the rat” element dominates the plot and the runtime, when the central story is about the Riddler. It introduces a lot of plot confusion that really doesn’t have to exist at all. Riddler is mad about corruption. Keep it simple.