Rettig made a guest appearance as a grown-up Jeff Miller in an episode of the later television series The New Lassie, with Jon Provost, which aired on October 25, 1991. The updated series featured appearances from two other Lassie veterans: Roddy McDowall, who in 1943 had starred in Lassie Come Home, the famous dog's first feature-length film, and June Lockhart, who had starred in the 1945 sequel Son of Lassie. Lockhart had also co-starred on the earlier television series, portraying Timmy's mother in the years after Rettig and Actress Jan Clayton left the show.