I have a LOT of these. I'm going to list several.
House. He never mocked 13's thinness because he was sure that sort of comment wouldn't bother her.
Wilson wrote that poem, not Syphilitic Granny Lady. Wilson just said she wrote that poem in case House laughed at it or otherwise didn't appreciate it.
Cameron was not just humoring that kid, she really does like video games.
Rick and Morty. There are several female Ricks. We just never see them because they all refused to join the citadel.
Cheers. The guy who Sam wouldn't let in the bar in the last scene of the final episode was Bill Clinton.
CSI. Hannah, the creepy little genius kid who turned out to be a killer in the episodes "The Unusual Suspect" and "Goodbye and Good Luck" has two more murders under her belt. In "Goodbye and Good Luck" it's mentioned that her parents died in a car accident. She rigged the car because she was pissed that her parents, who used to spoil her, got a lot more strict.
King of the Hill. Bobby grew up to be a professional comedian. He works in Las Vegas.
My Little Pony: Friendship is Magic. Blueblood is Luna's son. Celestia doesn't have any other siblings. Blueblood is a jerk because Luna gave birth to him and raised him when she was in her Nightmare Moon phase and encouraged him to be a jerk. She is now very embarrassed by him and there's a tacit agreement among the ponies not to talk about this.
MST3K. The reason the bots in the Netflix episodes have entirely different voices and personalities is they're not the same bots. The original bots are still on Earth living with Mike.
Popeye wasn't in Roger Rabbit because he would have taken one look at Judge Doom and kicked his ass and the movie would be over in fifteen minutes.
Lord of the Rings. Eowyn and Faramir=political marriage.
the Wizard of Oz. Dorothy doesn't have to worry about Miss Gulch coming back and getting rid of Toto. She was out riding her bike when the tornado hit.