Revealing mistake: It is very easy to tell when Salem is a real cat and when Salem is a robotic cat.
Revealing mistake: Near the end of the episode, Sabrina accidentally hits the football player in the eye by jumping happily. But you can see that Sabrina did not even touch him. (00:20:10)
Answer: In the S6 E18, "I, Busybody" Salem got permission from the Witch's Council to be human for one day to meet his pen pal, Roxie. It was all a point of view camera shot.