Feynman wasn't one of the top guys on the project, he was low-mid level. There's an entertaining lecture somewhere on Youtube where he talked about his time the

Feynman wasn't one of the top guys on the project, he was low-mid level. There's an entertaining lecture somewhere on Youtube where he talked about his time there; most of the time he was buried in computational work and sometimes inspecting chemical plants. He usually wasn't in the rooms where Big Important Decisions were made, which is what this Nolan film spends a lot of time on.