In Duckburg and indeed, the entire Duckverse, gold coins lack the density that they have in the otherwise 'normal' universe (our Earth) and therefore, a person (or, rather, a duck-person) can dive and swim through them.
In the animated short "Mickey's Christmas Carol" (1983), the young Scrooge McDuck's fiancée was portrayed by Daisy Duck. Daisy Duck is the girlfriend of Scrooge's nephew (Donald). Scrooge and Daisy had only one scene together in the short, and as in the original novel, they do not kiss or show any affection toward each other. Despite this, this seems like tremendously awkward casting unless, of course, the short took place in an alternate parallel universe where the characters all lived in Victorian England. I would ask native Oregonian Carl Banks about this controversy, except he died in 2000.