Actor Allusion: When Lewis asks Wilbur what his currently-absent father looks like, Wilbur lies and says "Tom Selleck." When Wilbur's father shows up at the end of the film, he looks nothing like Selleck, but he sure sounds like him... This is actually a kind of reverse Actor Allusion: the scene was written first, and gave the director the idea to offer Selleck the role.
Played straight with international releases, where the "Tom Selleck" line is replaced by whoever's playing Cornelius (the exceptions being the Brazilian, Dutch and French releases).
There's also an Author Allusion, as Goob's baseball team is the Dinos, whose mascot looks an awful lot like Dinosaur Bob.
Executive Meddling: In a good way. When Disney bought Pixar and John Lasseter took charge of Walt Disney Feature Animation as well, about a third of the movie was redone to improve on the story. However, the old guard almost revolted at it and openly expressed to the press that they hoped the film would bomb.
Talking to Himself: Ethan Sandler voices no less than seven characters, mostly among the Robinson family. Director Stephen Anderson is the Bowler Hat Guy, Grandpa Bud, and Cousin Tallulah. ...yes, a female Robinson family member has a male voice for no reason!
Throw It In: Wilber's line about his father looking like Tom Selleck was intended to be a placeholder until the writers came up with something better, but not only did the line stay, they actually got Tom Selleck to play Cornelius Robinson!
What Could Have Been: Disney bought the rights to "A Day with Wilbur Robinson" in the 90s with the initial intention of doing a live-action film directed by Peter Jackson