Ickis is voiced by Charlie Adler, meaning that this cartoon is the first time he played a red monster (only Charlie uses the "spastic, cowardly runt" voice for Ickis, not the "smug, hammy asshole" voice he uses for The Red Guy and Mr. Bighead).
Tim Curry is the voice of the Snortch's assistant, Zimbo. What's really disturbing is that you can't really tell that it's him, but you know there's something unwholesome and vaguely familiar about the voice.
What Could Have Been: There was originally going to be a film adaptation of the show by Klasky-Csupo, Nickelodeon Movies and Paramount Pictures after the success of the first Rugrats film. The idea was canceled after the film would be considered too dark for kids.
The characters got their start as just drawings on a napkin during lunch. Later, a storyline was developed around them, and the rest is history.