Black cat characters were popular at the time. Felix the Cat and Beans the Cat were just two of many.
Betty's home has all the latest fashionable furnishings, which Depression-era cinema audiences would have enjoyed seeing. The movies was one of the few places struggling Americans could escape for a few hours, at a bargain price.
Mama cat and crew are under the influence of catnip, which the censors actually allowed. Its effects in the feline population look similar to that of alcohol in humans. Catnip is also a folk remedy (for humans), used to treat stomach upsets and insomnia. In Great Britain, its cousin is catmint.