Deliberate mistake: During the dance number in the Dead Bar, the blue pirate has a sword stuck through him with the handle in the front, later it changes to the back, then to the front again. Seen when the groom falls back and grabs the handle, then picks the pirate up and drops him. (00:19:15 - 00:20:05)
Deliberate mistake: During the fight scene, the Lord takes an overhead slice at Victor with his sword. Victor catches the blade in the tines of the fork. However, if you look closely, the sword is moves from between the the first and second tine to between the second and third tine. (01:09:10)
Answer: A search on Google for sheet music just shows the titles of the tunes to be how they are listed on the soundtrack: Victor's Piano Solo, or Corpse Bride (Main Theme), or The Piano Duet. A web site (http://www.bluntinstrument.org.uk) suggests that "Victor's Piano Solo" appears to ape the famous moody first movement of Beethoven's 'Moonlight' piano sonata.
GrafSpee