That certifiable Firesign Theatre bunch, led by Philip Proctor and Peter Bergman, is back on the job in J-Men Forever. This time the Firesigners get their mitts on miles of footage culled from several Republic Pictures serials of the 1940s and 1950s. The dialogue emanating from the Republic actors has virtually no relation to what they were really saying. Instead, the footage had been re-edited and dubbed over to form a cockamamie scenario concerning an invading Lightning Bug, which will take over the world by utilizing insidious rock 'n' roll music unless the J-Men get their rears in gear. Like Woody Allen's What's Up, Tiger Lily?, J-Men Forever is a one-joke movie, but that one joke is worth a million laughs.
~ Hal Erickson, All Movie Guide