The theme within the film, a child believed to be on the verge of insanity because she lives in a fantasy world, was personal to producer Val Lewton who behaved in a similar way as a child. His wife has said that she felt he never truly entered the real world as an adult.
Although this sequel to Cat People (1942) is said to have nothing to do with the original film, in reality it is a continuation in the sense that the same actors (Kent Smith and Jane Randolph) play the same characters (Oliver Reed and Alice Moore) who fell in love at the end of the previous film. They are here married and have a daughter. Also, Irina (Simone Simon), who was the first Mrs. Reed, plays a prominent part in this story. However, this film has nothing whatsoever to do with the "cat people" of the original movie, nor with any curse.
The "magic mailbox tree" fantasy/lie told to Amy by her dad mirrors a story Val Lewton's dad told him when he was a kid, only Lewton had put his sister's birthday party invites in the tree, not his own as Amy does in the film.
The mummers' plays referred to by Alice and Miss Callahan are old folk plays performed by travelling groups of players called mummers or guisers. They were often performed in the street or in taverns/ public houses.
According to the screenwriter DeWitt Bodeen, Val Lewton wanted to call this film "Amy and Her Friend". However, RKO executives insisted on using the "Cat People" name to attract fans of Cat People (1942), which had been an enormous box office success made with a very low budget.