Lots and lots of info.
The lab theory is pretty much confirmed at this point. The kids and subjects, and the skull probably belonged to a giant that attempted a rescue. VP isn't behind this, so this M is an entire new enemy, which is awesome. My guess is that he is creating powerful hybrid monsters, similar to what Shiki did in strong world.
VP's tech is present here though, maybe Franky will find something useful. And finally, Holy shit. This was the site of Akainu vs Aokiji after all, and the battle clearly was intense and epic in scale. I bet Aokiji will tell us what happened through a flashback in the future.
The SHs playing heroes again, but there are children at risk, it would be hard to refuse. What was that gas thing ? M might have a weird DF. I want to know more about the chemical incident and VP.