Little Endora, one of the child witches in Darrin's dream, is Maureen McCormick, who later played Marcia Brady on The Brady Bunch (1969).
As the episode begins, Samantha is swimming in her backyard pool. While gardening in her front yard, Gladys Kravitz sees Samantha dive into the pool and sees the water splash. Problem is, the Stephens' backyard is not visible from the Kravitz home. The backyard is behind the home with its' view blocked by the house. This is the only episode that shows the backyard visible from the street.
The first time Larry calls Darrin a "son of a gun," which will become kind of his recurring phrase for Darrin. He says it to him four times.