The Simpsons have been a television staple for a very long time (some might say too long). From their debut on The Tracey Ullman Show as a series of shorts as a substitute for creator Matt Groening's very own Life in Hell, to the airing of their lasted episode ("Bart the Bad Guy", SE31E14) this past Sunday, America's Favorite Family has undergone a number of changes both subtle and obvious in their 30-plus years on air.
Most of the changes occurred in the show's early years. For practically every TV show, the first two seasons are regarded as a tumultuous growing period were ideas are tested and adjusted and revised (and in some cases cut completely) until a working, consistent formula can be found.
No more is this more apparent in The Simpsons' inaugural season, which sees a noticeably-different voice for Homer Simpson and a dark-skinned/purple-haired Waylon Smithers (the latter cut due to the unintended racial implications of a rare POC character subservient to an old white man). But some of these changes were even more severe, and could have fundamentally changed the direction of certain characters.
As revealed on a Season 4 DVD commentary, Matt Groening originally intended Marge Simpson's iconic blue beehive haircut to disguise a hidden pair of yellow rabbit ears. The show's (as yet unproduced) final episode would've revealed the Simpsons matriarch to be one of the anthropomorphic rabbits from Life in Hell. Groening cut the idea for being too fantastical and creating too many inconsistencies, and its since never been revisited or referenced on-air.
However, like the infamous blue-shirted Bart that appeared on some early merchandise, this idea did see life outside of the series proper. In The Simpsons Arcade Game, the rabbit ears are visible beneath Marge's hair during an animation where a vaccum cleaner pulls her hair down, and again when she is electrocuted and briefly turns transparent. The presence of this cut concept likely comes from the fact that producers often use early concept and reference art when creating merchandise, not taking into account changes that may occur from them to the actual release.