When Mrs. Oleson reminds Caroline to attend to the other customers in the restaurant, Caroline tells Anna that "Mrs. Simon Legree calls." This is a reference to the plantation owner in the novel "Uncle Tom's Cabin"; essentially, Caroline is calling Mrs. Oleson a "slave driver."
As the former fiancé of Harriet Oleson, William Schallert's character repeats a detail in a plot developed many years earlier for the TV sitcom The Patty Duke Show (1963), specifically, in The Christmas Present (1963), where his character mentions that he once vied for the betrothal of young woman named Harriet Oleson.
Second appearance of William Shallard, before as Tax collector and then pastor Russell
Mrs Craig's house is the same one Miss Cooper lived in, with a few changes to the furniture and garden.