Caroline In The City to Melrose Place (2009)

Fraiser's Niles and Daphne read Caroline in the City's comic strip.

John Larroquette Show's John Hemingway called into Fraiser's show

John Larroquette Show referenced Yoyodyne. Yoyodyne was also a client of Angel's Wolfram & Hart.

Angel was a spin-off of Buffy the Vampire Slayer.

The X-Files? Cigarette Smoking Man and Buffy the Vampire Slayer's Spike both smoked Morley cigarettes.

Brenda Walsh picks up a Morley smoking habit while in Paris on Beverly Hills 90210

90210 was a continuation of Beverly Hills 90210 years later

Melrose Place (2009) was a continuation of Melrose Place which was a spin off of Beverly Hills 90210 that was continued as 90210