At about 7:30 in the episode, Frasier has just announced to Martin and Daphne that "Freud is the poor man's Jung". As Niles is responding, "I never thought I'd live to see the day -- perhaps this is why I was spared", watch John Mahoney. It seems he's confused as to whether or not they're filming. He seems to check with someone in front of the stage, then looks up high behind himself as if to check a monitor. Finally, he looks straight at the camera.
Mrs. Moon: He's rich and you don't have to sleep with him. Rub it in.
Title: Don't Go Breaking My Heart
The episode title shares the same name as 1999 Romantic Comedy "Don't Go Breaking My Heart", for which Jane Leeves appeared in. This is also the title of a 1977 #1 duet by Elton John and Kiki Dee.
During this episode, Niles becomes addicted to soap operas. This quote is used at the beginning of every episode of the long-running soap opera Days of Our Lives. Interestingly, Millicent Martin (Gertrude Moon) starred on Days of our Lives in 1999.