The name of the episode is a homage to the 1925 novel The Great Gatsby and the 1974 film of the same name
Homer realizing that Marge opened a small store specializing in adorable items named Peppermints and pussy willows store, Lisa became her assistant, and Bart was presumedly dead is a reference to It's a Wonderful Life, where George Bailey (James Stewart) realizes that Bedford Falls has turned into a Vice City named Pottersville.
This is the first hour-long episode of the series.
This is the second episode to be in two parts (third if you count "The Simpsons Guy"). The first was "Who Shot Mr. Burns? (Part One)" and "Who Shot Mr. Burns? (Part Two)". Both episodes also featured Mr. Burns as a major character although the exact role was different (Specifically, both "Who Shot Mr. Burns" episodes had Burns as the central antagonist, while in "The Great Phatsby", Burns was the main protagonist).
When Common Sense is recording his rap verse at the end he yells "peace", but instead of doing a peace sign he performs an offensive hand gesture.
When Homer sees Goosey G eating, he states that he eats the same way he does; without "swallowing". He meant to say "chewing".