Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Nightmare Fuel: The Star Wars Holiday Special
Five words that ought to horrify any Star Wars fan: The Holiday Special is canon.
No, it isn't. George Lucas has stated point-blank that if he could, he'd take a sledgehammer to every single copy. Certain specific things in it have been accepted into canon, but the special as a whole is not.