Near the begining Jiji lampshades the fact that he and Kiki are out-of-the-ordinary, with his usual charm.
Jiji: You'd think they'd never seen a girl and a cat on a broom before.
Just about every scene with Jiji in it is a CMOF, it helps that his dub voice actor was the late great Phil Hartman.
When Osono tells her husband, The Quiet One and local Gentle Giant shes about to have her baby. If the look on his face isn't funny enough, the fact that the first thing he does is run straight into a table would make anybody burst with laughter.
"KET, TURN OFF THE TV!"
After Kiki saves Tombo, the janitor that she borrowed a broom from says "That's my broom she used!"