The Flying Dog website says they use blood orange peel (read: zest, no white part) and juice. The hops are Warrior, Citra, and Galaxy, and I figure that combo helps make it more citrusy.
I have gotten good orange flavor and aroma using zest in the last 5-10 minutes of the boil. One time I put 2 cups freshly squeezed Cara Cara orange juice at flameout in a 5-gallon Hitachino Nest white ale clone, but couldn't detect much orange from it. I didn't get vomit, though. I think increasing the amount would've helped give it more of a citrus tang.