Factual errors: Although Mathilde herself in narration, and her aunt in the story, say the musical instrument Mathilde plays is the tuba (in French), yet any euphonium player can easily recognize the musical instrument shown as a euphonium by seeing its clear images and listening to its sound, which is a little different yet crucial from those of tuba. This mistake might be deliberately made, for a real tuba might be so big for Mathilde that the view could not be taken appropriately.
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