Mary Costa, the voice of Aurora in La Belle au bois dormant (1959), is the only living original voice actress not to reprise her Disney Princess, as she was 88 years old and had retired from acting.
(at around 53 mins) A non-speaking Stan Lee avatar can be seen in a brief cameo while traversing the Internet.
(at around 1h 40 mins) The mid-credits sequence shows a memorable scene from the first Ralph Breaks the Internet trailer that ended up being cut from the final film. As a meta joke, the little girl in the mid-credits scene prefaces the gag by telling her mother that while she enjoyed the movie, she's annoyed that there was a scene from the trailer that didn't show up.
Merida and Buzz Lightyear are the first major characters from a Pixar Film to make their first full appearance in a film not by Pixar.
(at around 1h 3 mins) To get Vanellope's song really Disney-ish, Alan Menken was asked to compose it. Menken, along with his songwriting partner Howard Ashman, is responsible for all the catchy tunes in La Petite Sirène (1989), La Belle et la Bête (1991), Aladdin (1992), Pocahontas : Une légende indienne (1995) and others.