The film's popularity almost led to a spin-off TV series in 1989. When the animation department green-lit The Rescuers Down Under (1990), the spin-off was reworked into Chip 'n Dale: Rescue Rangers (1989), with Chip and Dale replacing Bernard and Miss Bianca.
One of Miss Bianca's traits, as portrayed in the original novel, was her trust and affection for felines (widely known as menacing predators of mice). This element was brought onto the film in the form of Rufus the cat. Though he frightens the mice duo initially, he quickly shows he is a friend and is willing to help the mice on their quest to find Penny, with whom he shared a special friendship.
In the scene where Penny is seen carrying Rufus the cat off to supper, Penny grabs Rufus and uncomfortably carries him off in her arms, pushing him up with her knee as he begins to slip. Ollie Johnston, who animated this scene, explained that he did this in order to show the tender affection between Penny and Rufus, by having the cat be too fond of Penny to complain, since it would have been easier for Penny to walk away and have Rufus follow her.
The Rescue Aid Society honors their founder, Euripedes Mouse, who removed a tiny needle from a ferocious lion's paw, a clear reference to the classic Aesop fable, "The Mouse and the Lion."
Considered by its producers, critics and audiences to be the film that proved that Walt Disney Productions' animation department would survive following the death of Walt Disney. It was the company's first major critical and financial success since The Jungle Book (1967), and its last until The Little Mermaid (1989). Despite its high budget (for the time period), the film proved a huge success, managing to out-gross strong competition, such as Star Wars: Episode IV - A New Hope (1977), in several European countries, including France and West Germany.