Finn´s Trivia

In the original short he was called Pen, like his creator, Pendleton Ward, but in the original comic he says that it was cause he loved pens

Finn carries his adoptive mother's music box in his pack and knows her lullaby by heart

Finn cries rarely only in such devasting situatios as hearthbreak, and dead

Although the fear to the sea desappeared, It

is unknown whether other fears Finn (As fear of Lich or the Clown Nurses) disappeared since Finn broke it in half with the Sword of Grass.
                                                        

Finn is technically still the King of the Goblins; the goblins believe his scapegoat, Whisper Dan, to be him.