The reference to "very special episodes" is #6. The reference to Full House (1987) is #5. The reference to the history of unexplained character recastings gets an honorable mention.
The family is painted from a pencil outline in the opening credits. Also, Billy says "Sit, Sparky, sit. Good boy.", a reference to the Ubu production company tag heard at the end of every Family Ties episode.
In the opening credits, there are photos of each character at different ages, up to their "current' age in the sitcom, just like the credits in "Growing Pains."