No witches were ever burned in the United States.
The introduction to the "Spark of Life" segment claims that it takes place in the 1800s, but costumes and equipment, including a telephone, are modern.
The Transylvanian Count's castle perches high on a cliff above the ocean. Transylvania is a landlocked region, far from the sea.
In "The Witches Clock" episode, Actor Roger Gentry flubs his line: "I'm getting...We've got a lot to do, and I'm getting hungry!"