This episode contains several pieces of information about witches that would be contradicted in subsequent seasons.
1. Samantha says that her mother, Endora, gets so upset over Halloween each year that she flies to the South of France "til it all blows over."
In a later episode, however, Samantha (and Darrin, by proxy) gets invited to her mother's "annual" Halloween bash.
2. Bertha makes the comment that, if the mortals ever did find out that they were witches, they'd better take out lots of fire insurance. Samantha comments, "Oh Bertha, they stopped burning us years ago."
In a subsequent episode, Samantha and Darrin find themselves in old Salem, and Samantha makes a speech about how the people they've put on trial couldn't possibly be witches because no mere ropes or binds could hold one; she then causes her own binds to disappear.