This episode is commonly called "The Backwards Episode"; and all events in it take place in reverse chronological order. On the Season Nine DVD set however, there is a feature which allows the viewer to watch this episode play out in normal chronology.
The backwards episode "The Betrayal" is based on a Harold Pinter play, "Betrayal," which also uses the same gimmick. Sue-Ellen Mishke's (Brenda Strong) fiancé in the episode is named Pinter in tribute to the playwright.
When Kramer (Michael Richards) tells Jerry (Jerry Seinfeld) & George (Jason Alexander) he had been getting dirty looks from FDR, they ask him if it was the crook-eye or the stink-eye. This references episode 8.14 The Van Buren Boys (1997), when Kramer said he was given the stink-eye and he returned fire with the crook-eye.
The expression "You can stuff your sorries in a sack, mister" is used throughout this episode and is a reference to The Odd Couple (1970) episode entitled Strike Up the Band or Else (1974).
In The Apartment (1992), it is established that Kramer initially subleased his apartment from Paul Buchman, and that Paul had been living in that apartment when he met and dated Jamie. Paul knew Jerry, because he asked Kramer about him. But in the flashback of this episode, which takes place six years earlier than the "Mad About You" episode, Jerry moves in and Kramer is already living in the apartment. According to the chronology of "Mad About You," Paul should have been living there at the time Jerry moves in.