You know who was even worse than Whedon about recycling old works? Michael Landon. He used music, plots, dialogue, and sometimes even entire scripts from "Bonanza" episodes in his TV shows "Little House on the Prairie" and "Father Murphy." I guess he thought that enough years had passed that viewers wouldn't recognize it, but he forgot about how often Bonanza was being rerun and that many of us viewers had seen the Bonanza episodes multiple times. I remember watching a Father Murphy ep in which Murphy and his pal traveled to a new town and got mistaken for famous outlaws -- it was the first time this Murphy episode had aired, but I found myself reciting the dialogue with the characters word-for-word, because I had seen the Bonanza version, with Hoss and Candy in the roles, so many times that I'd memorized it!