When Disney was trying to develop a Mickey Mouse feature film in the early 1940s, one of the ideas considered was "The Three Musketeers," but it was abandoned because the original novel requires four main characters (the titular musketeers and D'Artagnan), and the filmmakers found it difficult to come up with a good combination of established characters to fill the parts. Sixty-plus years later, the problem was solved by having Mickey, Donald and Goofy not play the original Three Musketeers and thus tell a story that parallels the original, but is not strictly an adaptation of it. The original Musketeers, incidentally, are the ones who saved the gang in the beginning of the film, and their autographs are in the hat they give Mickey.
Goofy is the only main Disney character (out of Mickey and Donald) to not appear in his classic outfit.
Pete sports his once-trademark peg leg for the first time since the 1930s.
The opera featured in the movie is "The Pirates of Penzance."
Aside from the ending scene in Topolino e la magia del Natale (1999), this was the first feature length movie starring Mickey Mouse, Donald Duck, and Goofy together.