They actually did do one other Disney Afternoon show as a theatrical movie, A Goofy Movie, which was basically a Goof Troop movie, and also one of the best movies ever made in human history. Duck Tales was a better show, but Goofy got the better film.
Yep, and it got a sequel, An Extremely Goofy Movie. Max was aged to a teen in part because of the death of his original voice actress.
Always liked The Ducktales Movie, Disney must have as well, Aladdin (which was released 2 years later) seemed to reuse chunks of the plot.