When Leo takes a cartridge/bullet out of the souvenir box, shows it to Camille and her father saying there is blood on it, the father says the bullet ripped a child's leg. Yet we are shown an unused cartridge, not an actual bullet (the top of the cartridge).
When the cellist plays the prelude of Bach's first suite for violoncello solo, his fingering and bowing does not match in any way (to say the least) the music we hear.