Some of the writers also had experience on live-action projects. For example, Lance Khazel ("Whole Lotta Shakin'", "The Great Snipe Hunt", "Jujubombs" and "Sneeze, Please") also wrote Son of the Mask and Susan Sherman wrote for That's So Raven and Cory in the House.
A number of one-shot characters gave the voice actors some expanded range of voices. For example, in "Crowded House", the tour guide sounded like Betty DeVille and the excerise coach sounded like General Knowledge from Cranium Command.
Greg Proops from the U.S. version of Whose Line Is It Anyway? would often voice a one-time character when the plot demanded it.
Keep Circulating the Tapes: Pretty much the only way to see it these days if by chance is comes on Boomerang (it usually lasts for a month before getting shelved again). You'll be lucky if episdoes appear on Cartoon Network Video or YouTube.
The What A Cartoon pilot hasn't been seen since 1999. Its only records of existence were in a few promos leading up to the series premiere.