Gramps, played by George Cleveland, reveals that Lassie is about five or six years old. His revelation hints at the actual age of the collie playing the role in this episode, which was originally broadcast in February 1956. That collie was the son of the original Lassie, i.e. Pal.
This is the fourth of 43 appearances Arthur Space makes in the series, each time appearing as Doc Weaver, the local veterinarian. He takes over for Doc Peter Wilson, who is played by Frank Ferguson in season one.