In all the scenes with a piano, the keys that are played don't sound out the right melody. For example: Victor plays Middle C, but the sound that comes out is not Middle C, but D, sharps and flats are heard coming from white keys instead of black keys, etc.
During the dinner scene, as the camera pans up and down the
table, we can see that everyone (including Mr. and Mrs. Everglot) have some sort of chicken-like bird on their plate. However, when the "guests" arrive, Mr. and Mrs. Everglott's chicken turns into soup.
In the scene where Victor is in the woods saying his vows, he puts his ring on the "branch" aka the corpse bride's hand and he puts the ring on the pointer finger. But in the next shot when she says "You may kiss the bride." the ring has magically moved to her ring finger.
During "According to Plan" when Maudelaine Everglot opens the safe, you see she is wearing a gold wedding ring. However, when she closes it, the ring is gone. It reappears later. The same thing happens to Nell Van Dort. In one shot she has her ring on but in the next it's gone.
When Victor is practicing his vows, he is having difficulty lighting his candle. Victoria, who is standing next to him, is also holding an unlit candle. However, a few seconds later, she surreptitiously lights his candle with hers, which has mysteriously lit itself.
During the Wedding Song, a baker's nose gets knocked off and mixed into the wedding cake batter. Towards the end of the song, while they're carrying the cake through the street, his nose is back with no signs of damage.
When Victor is first talking to Victoria, he's fiddling with his tie. In one shot it is out of his jacket and wrinkled but the next time he's shown, the tie is tucked in and there isn't a wrinkle in sight.
When Barkis and Victor are fighting, Victor blocks the sword with the fork, and at first, the blade is to the right of the three prongs. The shot switches away, then back to Victor, and now the sword is between the middle and right prongs.
When Victor is taken to the "underworld" a piratical skeleton has a sword in his middle. The sword hilt is facing out of his chest, so the other skeleton could grab it. When Victor goes up and grabs the sword, the sword blade is sticking out of his chest.