Members of Mumford & Sons, Edward Sharpe and the Magnetic Zeros and Old Crow Medicine Show were on hand at SXSW in Austin to discuss Big Easy Express, a new documentary about the bands' joint trip from the Bay Area to New Orleans by train. It was a life-changing experience and a rather large undertaking, the musicians tell Rolling Stone: "I mean, it's a lot to hire a train," says the Medicine Show's Gill Landry.