The DARPA office is physically laid out to enabled people interact (similar to how supposedly the Pixar headquarters were designed.) Everybody is probably an expert on something and there is a culture people dropping and asking each other about the subject of their expertise (similar to Bell Labs didn’t have a unique model.) The culture also encourages PMs discussing their programs with other PMs. This is special because it would be easy for everybody to mind their own business asa everybody is working on their own programs. The fact that DARPA is relatively tiny and flat probably helps.
People who get DARPA funding are required to share research with each other at workshops. (Cloning DARPA Successfully - Article) Since they are all presumably working on different aspects of the same problem as coordinated by the program managers this seems valuable. It has some of the aspects of open science but much more focused and making sure the people who might really benefit from the knowledge know about it. This stands in contrast to normal academia where everything is first to post so people are worried about getting scooped so they pipet out information. Academic credit is a first-to-the post system.