Edie McClurg left the show during the third season for a full-time role on La famiglia Hogan (1986). During the last two seasons her character was referred to off-camera, and largely replaced by Brandon's sister Ida Mae.
As Tiffany Brisette grew older, she and her mother often insisted that she be given more to do and evolve the Vicki character with changes of clothes, speaking in a normal voice, and singing. There was frustration over Brissette not being able to show any acting range. The writers would also campaign to switch up the formula of the show to keep it fresh, but creator Howard Leeds wanted to keep the show as it was.
According to Emily Schulman, the main cast got along great and was one big happy family. However, the parents of the child actors on the show clashed and didn't get along. She even admitted that there would be tension between the child actors at certain points. The studio had to employ three separate on set tutors because the parents couldn't agree on one. Marla Pennington also sensed the tension between the parents and would stay out of it. She claims Tiffany Brissette's mother Diane was involved in many of the backstage arguments, often pestering the producers to show off more of her daughter's skills.
To explain Tiffany Brissette aging and growth spurt during the later episodes, Ted added a growth chip in Vicki so she can grow and catch up to the other kids and avoid suspicion. Production often skipped hiatuses as well due to fear of the child actors hitting puberty and aging quickly.
Despite Small Wonder being wildly popular with young audiences and becoming a ratings success, there was little licensing support for the series. Creator Howard Leeds wanted Fox to capitalize off Vicki's popularity by making merchandise, however these ideas never were implemented either. A Vicki Halloween costume was issued one year but never finalized. Ideas for a Vicki the Robot doll never made it past the prototype stage. A cartoon was discussed at one point, then dismissed. Fox, which had bought Metromedia, was not particularly fond of Small Wonder and had no interest in the series beyond giving it a two-year renewal made by Metromedia for it's third and fourth season. The show was extremely cheap to produce that it was virtually impossible to lose money on it.