Headscratchers / Professor Layton and the Eternal Diva
One thing I really didn't understand, and was never explained to my satisfaction, is why Amelia was chosen. Melina's father notes that he 'searched far and wide' for a 'special young woman' to receive a free ticket to the opera. Of course, the real purpose was to find a new house for Melina's memories and personality, I get that part - but what was so special about Amelia? She was supposed to be a gifted chess player. That didn't exactly guarantee that she'd have the vocal range necessary for Melina to sing the Song of the Sea. So why did they pick her?
I thought they picked her because she was capable of housing them, which was what was most important to Oswald, anyway. Not sure exactly why she was compatible, just that she was.
Presumably her compatibility was somehow linked to her intelligence level. She was, after all, one of the few to solve nearly every puzzle first. That would also explain why Oswald briefly tries to use Luke, who also did very well on the puzzles, as a fallback for his plan.
In regards to the Song of the Sea part, the vocal range didn't seem to be the issue. The problem was that Melina was the last person to know what the song was, so when she died, all knowledge of how to sing it was gone. Putting Melina's conscious in someone else's body would ensure that there'd be someone alive who could say what the song was. And if Amelia's body didn't have the physical ability to sing it, they could have just ordered her to write it down and found someone else to do so.
At the beginning of the movie the Professor says that the one who silenced Big Ben escaped from the room and then solves a puzzle to unlock the door but the puzzle he solves was covered in dust and still in the floor. How could the culprit get out if the puzzle wasn't solved when Professor Layton and Luke got there? Who reset it?
It was definitely an oversight. Either that or the Eternal Diva was given the format of the video game. Giving us, the players, the feel of needing to solve the puzzle ourselves, regardless of whether it was solved already or not. As for Big Ben being dusty, who cleans it up everyday anyway? Probably at least once a week or month.
Maybe I'm just missing something, but what exactly was the point of the entire shtick with the food and wine? The way it's presented makes it seem like it's important, but after everyone decides to just eat it, it's never even brought up again. Amelia specifically brings up that it could be a puzzle, so it seems especially out of left field how it's just never used afterwards.
They had arrived at the opera house around sunset (judging by the sunlight when Emmy drops Luke and Layton off), and the meal was given to them around late morning the next day. Descole probably knew that he needed to feed the contestants, and the potential of a puzzle was just Amelia being properly skeptical.