The Cornelius Coot statue originally appeared in the Uncle Scrooge comics. A real life version was built for Mickey's Toontown Fair at Walt Disney World.
The episode states that Della (and, therefore, Donald and the boys) are descended from Cornelius Coot, founder of Duckburg. This taken from the Duck Family Tree as drawn by famous Disney comics artist Don Rosa, who in turn based his tree on the ones Carl Barks drew privately and loaned out to Rosa. The fact that they are descended from a Coot was also mentioned in Legend of the Three Caballeros (2018), which had Donald inheriting an old adventurer cabana from his great grandfather Clinton Coot, who is also Cornelius Coot's son.
The mine that Webby and the Triplets travel through in a minecart is naturally reminiscent of the African Mines level from the DuckTales (1989) video game and it's remake DuckTales: Remastered (2013).
Della refers to Launchpad as "LP," which is what the titular character what call him in Darkwing Duck (1991).
Launchpad when telling Della about his crashes with the plane he'd been in so many crashes that he can crash safely better than anyone, which he also said in the episode The Uncrashable Hindentanic (1987) of the original DuckTales (1987).