This Is Us fans are waiting for Justin Hartley's costars to make guest appearances on Tracker - so why aren't there currently plans to bring them in? During an exclusive interview with Us Weekly, executive producer Elwood Reid explained that the CBS show is waiting for the perfect roles. "[We discuss it] all the time. If I'm going to go with those kind of big names, I got to make sure I have a story," he noted. "The show works because we're with Colter so much and he's just such an interesting actor that he's able to carry that big narrative load." Reid confirmed ongoing discussions.