User blog comment:TitanicMixGirl/Episode 9 I Made Up/@comment-190.237.3.207-20121229062421/@comment-190.238.159.232-20130101012046

Because Alex Hirsch said in a lot of interviews that one of his favorite cartoons was always The Simpsons and also said that inspired him a lot.

You can aslo realize it just by looking the face of the characters, they're pretty similar to the simpsons (and also the muppets).

And Alex Hirsch always mentions things like that in his Twitter. Like when he told Bill Oakley that he was a hero for him.