According to an interview with Craig Bartlett, "Arnie was a joke about when we get really ugly animation back from the studio. We turned that into an episode."
It's possible that Arnie might have some form of Autism, due to his odd behaviors, hobbies, and tone of voice.
When Helga says: "Oh Arnold, what is this thing called love?" you can clearly see in the background a cloud resembling Arnold's head shape.
The title of the horror movie "Evil Twin II" is a reference to the Evil Dead series. However the movie itself appears to be a slasher film with a chainsaw wielding serial killer akin to The Texas Chainsaw Massacre or Motel Hell.