TaleSpin

Mad Dog is actually Tabaqui.

We never see Tabaqui is Disney's adaptation of the Jungle Book, and Talespin has some Jungle Book characters in it like Baloo, Shere Khan and King Louie. Who's to say that Mad Dog isn't just some pirate nickname for him and his real name is Tabaqui? Also, Mad Dog and Tabaqui have very similar if not identical personalities. It could be possible that Mad Dog used to work for Shere Khan before he was fired for some incident and taken in by Don Karnage.

Kit is related to Rebecca, just unaware of the relation.

Kit was originally meant to be Rebecca's son and his design does look surprisingly like her. It's possible one of Kit's parents is an estranged sibling or cousin of Rebecca who never saw any reason to contact Rebecca about their kid before Kit was orphaned. Perhaps Kit is completely unaware that his boss could have a legal claim for custody over him and Rebecca doesn't even know that Kit as her relation exists.

• Alternatively, Kit is her son but neither of them suspects it because he had another name before being abducted and Rebecca refuses to hope her boy is alive.

Rebecca is from a wealthy family.

It would explain how she manages to live as a single mother and buy up a business; even accounting for the AU factor, it's probably still unusual for a widow to have business qualifications, let alone run a business essentially singlehandedly. However, if Rebecca is a Daddy's Girl of a wealthy man, it would make sense that he's her backer initially and eventually backs off because Rebecca wants to prove she can stand on her own.

The late Mr. Cunningham was verbally abusive.

He kept telling Rebecca to let a "man" run the family's finances and that's why she's constantly trying to excel in business.