Although completed in 2008, the film wasn't released until 2015. The reason for the gap was problems with music licensing rights. It took a Kickstarter campaign to raise the $200,000 to clear them.
Denny Tedesco originally planned for this to be a 30-minute filmed roundtable chat between some of the leading session musicians of the day. Instead, he found he was confronted with such a wealth of material that the natural solution was to turn it into a feature film. He says he has 6-1/2 hours of additional material not in the film and is still filming interviews with survivors of the Wrecking Crew era.
The Wrecking Crew got their name in the early 1960s because of their refusal to show up to recording sessions in formal suits. Instead, they showed up in jeans and T-shirts, causing some in the business to say that they were "wrecking" the high standards of the industry.
Whereas The Wrecking Crew was the heart of the L.A. / west coast sound, the rhythm and blues counterpart was the Muscle Shoals Rhythm Section, located in Alabama. The documentary Muscle Shoals (2013) tells that story.