In the party scene where Rose is watching Iris come down the stairs and move across the floor, Rose is carrying a tray with two champagne glasses. In the next immediate scene, the tray has only one glass.
Tuning forks cannot not ring out loud like a bell. Not on their own. They need to be held against some resonance chamber to produce a louder volume beyond their normal, barely audible hum.
There is now way that in 1926 a camera could take consecutive shots (with flash!).
It is stated that the comet Kharon (spelling taken from closed captioning) comes every 70.6 years. The Melody time-line takes place in March 1994. 70 years prior is 1924, but 70.6 years would place the comets appearance in fall of 1923, not 1924 when the ritual took place.
Contrary to what the introduction video claims, there is no comet named Kharon. One of Pluto's moons is named Charon. Consequently, the whole story of the comet splitting up is not true either.
During the chanting scene, the word "spirit" is misspelled "sprit"