Gilligan's Island to Out of the Blue
5 connections
Gilligan's Island
Meego
Meego (who was an alien) tried to contact his mother on the home planet by phone and instead the phone connected with Gilligan, Mary Ann and the Professor on Gillian's Island
Family Matters
Family Matters' Urkel appeared in the first two episodes of Meego.
Perfect Strangers
Family Matters was a spin-off of the character of Hariette and Carl Winslow from Perfect Strangers
Happy Days
Perfect Strangers' featured a game show segment in which the toilet was provided courtesy of Cunningham Hardware in Milwalkee, WI, owned by Howard Cunningham of Happy Days.
Out of the Blue
Out of the Blue was a spin-off of Happy Days