This article is from the The Simpsons FAQ, by Ondre Lombard wakkojr@nospam.wcat.com and Andrew Gill superluser@mail.rit.edu with numerous contributions by others.
Sort of. When "Homer's Odyssey" was being produced, Smithers was
accidentally animated with the wrong color. This goof is entirely the
fault of Klasky-Csupo and Producer David Silverman assures us that Waylon
was always meant to be yellow.
David suggests that you imagine that Smithers had just come back from a
vacation in the Caribbean with a deep tan when the episode took place.
 
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