Back in December, Riley Green hinted that he would soon be appearing in a television show. Is “Marshals” that show?  In a new trailer for Season One of the “Yellowstone” spinoff, fans believe a mysterious guitar player may indeed be Green. A quick glimpse of a man playing guitar in a campfire scene has Internet detectives convinced that this is the role Green had teased months ago. We could know more in a couple weeks; “Marshals” premieres Sunday, March 1 (8:00–9:00 PM ET/PT) on CBS and Paramount+.