The end plots Troy McClure references haven't all happened, however Selma marrying multiple people has happened in the show as she married Fat Tony and Abraham Simpson and Homer seeing a tiny alien named Ozmodiar did come true in a scene when he ruined the power plant in HOMR.
Lisa appears with one line in Chief Wiggum P.I. It is announced she is replaced in The Simpsons Family Smile Time Variety Hour, which is a likely spoof of the 1977 spin off The Brady Bunch Variety Hour. Eve Plumb refused to participate in this spinoff (she didn't want to appear in all of the planned episodes), so she was replaced by another girl playing Jan Brady.
Homer is the only family member to appear in all three stories.
When Kent Brockman is announcing the debut of The Simpsons Smile Time Variety Hour a clock is behind him reading 8:20, which during the episode's debut, was the approximate time that segment was aired for households that went by Pacific Standard Time and Eastern Standard Time.
The sound that comes out of The Sea Captains Pipe in the episode sounds like Stepney the Bluebell Engine's whistle from Thomas the Tank Engine.
Magnum P.I. - The title of Chief Wiggum's skit is a reference to the famous TV show.
My Mother the Car - The "Love Matic Grandpa", where Moe's Love Tester is possessed by the spirit of Grandpa, is a spoof of this Jerry Van Dyke show, where a man buys an antique car to learn that his deceased mother is communicating to him through the car.
The Smothers Brothers Show - Not to be confused with their better known variety show, the animated opening credits of this sitcom (in which Tommy Smothers dies and becomes Dick's guardian angel) are parodied as the "Love Matic Grandpa" opening credits.
2001: A Space Odyssey- When Grampa/Love Machine was beaten in the bathroom, he sings 'Daisy' while in pain. This is a reference to HAL 9000 singing 'Daisy' right before his higher thinking was deactivated.