What were muses doing living in a castle, anyway? Shouldn't it have been "Barbie and the Diamond Temple?"
Castles are cool, and it would break the kids' minds to have their beloved Barbie princess living in a temple.
Why did the dogs dance anthropomorphically when they never did anything else that way? I mean, other than the dancing they acted (mostly) like regular dogs.
Seeing as how they are in a magical musical land, maybe the song/music enchanted them and gave them the ability to dance that way.
Why did Melody keep singing? The first time is (somewhat) understandable, as she hadn't sung or heard music in a long time and she had just made friends with the girls. But why at the inn did she sing along? She obviously knew that Slyder could detect her in such a way. And she saw how he destroyed Alexa and Liana's home because of her. I'd think she would had figured that keeping her trap shut off from singing would be the first thing on her mind.
She didn't know Slyder could hear her singing until he'd found her. After that, she certainly keeps her trap shut. The better question is, how did Lydia rig up Slyder to detect Melody's singing? And if she could do that, how could she still not find her?