Kramer's (Michael Richards) refusal of wearing the red ribbon while doing the New York City AIDS Walk caused a lot of controversy, and was inspired by real events. Every year when the cast & crew went to the Emmy Awards, they were asked to wear the same ribbon for the ceremonies. Writer Peter Mehlman said that none of them saw the need to do this (wearing a ribbon doesn't cure the disease and everybody was already aware of it) and he took great pleasure in satirising the whole idea in this particular episode.
The Today sponge "was manufactured until 1995, when FDA imposed new manufacturing standards." The product had several setbacks while marketed, including a link to toxic shock syndrome. In 1998 Allendale Pharmaceuticals acquired the rights to the Today sponge, and it was once again available. New FDA standards for manufacturing and record-keeping forced repeated delays, but the Today sponge was finally re-introduced in Canada in March 2003, and in the U.S. in September 2005.
Elaine (Julia Louis-Dreyfus) paraphrases Tommy Lee Jones' famous "hard target search" speech from The Fugitive (1993) when she finds out the sponge has been taken off the market and needs to stockpile them.
When Jerry opens up Lena's closet, at least 12 cases are visible above Jerry's waist level and probably another 12 boxes below that are outside the camera's frame - 24 cases at 60 sponges is 1440 sponges. The spermicide on the sponge was good for about 2 years before it expired. Lena could have sex twice a day, every day, for two years before her sponges lost their effectiveness.
This episode was written by Peter Mehlman. One of the initial story lines of this episode was Kramer (Michael Richards) & Newman (Wayne Knight) buying stocks in the contraceptive devices as Kramer had heard a rumour the sponge was going out of business.