In the final episode, the song playing when Ross and Rachel have their final on-screen kiss is the same song that played when they had their first kiss.
This is the first, and only time that we see Ross' bedroom in his current apartment.
At 15:40 when you first see Monica and Chandler holding their newborns, the nurse on the intercom is paging Dr. Matthew Perry.
The final episode drew an audience of 52.5 million people, when it was first shown in the USA. This was the fourth most watched finale in US television history. As a matter of fact, The One After the Superbowl: Part 1 (1996), in season two (aired 28 January 1996), had higher figures with 52.9 million viewers.
The cast members were very emotional filming this episode. Their crying was genuine.