Kirk takes the wheel as “Music Raygun” goes back in time to the 1970s, when everything was bright and shiny on the outside, but sort of washed out and profoundly bleak beneath the surface. That's right: It's our disco episode. There’s Travolta, “Dance Fever” and, of course, a “Soul Train” line. That’s all to be expected. Less expected is… Ethel Merman? And don’t worry; we also sit through “Disco Duck.” Yeah. We do that. For you. All this, plus a fish saves the city of Pittsburgh.