The Koala in Platypus Duck's diner complaining "There's a dog in my soup" is a play on the comedy routines that begin with "There's a fly in my soup".
Vincent Van Ghoul does not recite a poem at the beginning of this episode, as he usually does.
This marks a rare time where a ghost's plot was completely off Vincent's radar. He offers no assistance or advice to the gang: in fact he had no idea something was wrong. He behaves very out of character, like a lazy crotchety grandpa rather than a wise sorcerous mentor. This may be because he was unwell.
Most of the comic strips are based on real-world ones; Missing Link is inspired by B.C. and The Wacky Wizard is inspired by Wizard of Id. Platypus Duck appears to take some inspiration from Pogo the Possum (particularly the earliest version, where Albert the Alligator was a villain rather than the hero he later became). Astrid 2000 has some similarities to Buck Rogers and/or Flash Gordon.