The album is unique for Beck in that it is composed mainly of vocal songs, save for two instrumentals in the form of "Escape" and "You Know, We Know" (each written by his longtime collaborators Jan Hammer and Tony Hymas respectively). Designed to be a foray into pop music in order to capitalise on that sound at the time, it was produced by Nile Rodgers for that reason. Such was the desire to score a hit album, Beck uncharacteristically found himself singing on "Get Workin'" and "Night After Night", at the insistence of Rodgers. "Ambitious" and "People Get Ready" feature a rare instance of Beck playing a Jackson Soloist rather than his usual Fender Stratocaster. Despite its success, he has since expressed his disdain for the album, calling it a "record company goof" and "a very sad sort of time" for him.
The CD edition of Flash included two bonus tracks, "Nighthawks" and "Back on the Streets", which were originally released as B-sides. Another track from the album's recording sessions, "Wild Thing" (a cover of The Troggs), was released only as a promo single and never on the album, but would later be featured on Beck's 1991 compilation album Beckology.
Flash has received mixed reviews. Stephen Thomas Erlewine at AllMusic gave it three stars out of five and described "People Get Ready" as "a fine performance".David Fricke at Rolling Stone called the album "one of Beck's best ever" and praised it as having "awesome guitar prowess and startling commercial daring", but remarked that the collaborations with Rodgers and Baker "almost don't work".Robert Christgau at The Village Voice gave it a 'B' grade, labelling it as "funk-metal fusion" and "the best LP of [Beck's] pathologically spotty career"; the latter due to Rodgers' production.