The only issue I immediately took from the film was that in certain segments, the actual filmmakers were interviewed with the same gravity as the experts and witnesses that the filmmakers were supposed to be learning from. I'm sure that the reasons for this were to build narrative where there was no convenient expert witness, but interviewing the filmmakers smacks of an author citing his own prior work to defend his hypothesis.
All in all, A Noble Lie is a must-see if you want to learn more about the OKC bombing, the mysterious murders which followed it, the government sponsored tests which blow the "lone truck bomb" theory out of the water, and the government which continues to cover "someone's" tracks to this day.