The U.S. West Coast airing of the finale of Seinfeld coincided with the death of Frank Sinatra. Sinatra's ambulance was able to arrive at his home and then to Cedars-Sinai Medical Center very quickly in light traffic, due to many in Los Angeles being indoors to watch the show.
This was the fifth most-watched television finale of all time.
Because of the immense amount of scrutiny around the plot of the final episode, security during production was high. Audience members who attended the taping (most of whom were family and friends of those involved with the show) had to sign affidavits swearing not to reveal the events of the episode.
On the night the finale aired, TV Land paid tribute by airing no programming during that hour, instead showing a closed TV Land office door with handwritten signs that read: "We're TV fans so... We're watching the last episode of Seinfeld. Will return at 10pm et, 7pm pt."
There was enough material recorded for this episode to fill three half-hour episodes. In the end, the full show runs 55 minutes, the longest episode in the show's nine-year history.