Character mistake: At the beginning Sally follows Jack at the end of the Halloween celebration where he sings "Jack's Lament." She then goes off to gather more deadly nightshade. Look at Sally when she sits down. It is in front of a stone labeled "witch hazel" and "deadly nightshade" is seen next to it on the right. Yet, Sally pulls two pieces of witch hazel out of the ground, before a quick cut back to the lab where we see her putting it in a jar marked "nightshade".
The Nightmare Before Christmas (1993)
1 character mistake
Directed by: Henry Selick
Starring: Catherine O'Hara, Chris Sarandon, William Hickey, Danny Elfman
Continuity mistake: After Jack is blown out of the sky and is lying in the graveyard, he has several grey smudges on his face from the explosion. But in the very next shot, a bird's eye view of Jack lying across the angel, the smudges have disappeared. (00:59:10)
Trivia: At one point during the song "Jack's Lament", Jack pops up between two tombstones. The tombstone on the left is a figure from the painting "The Scream", and the tombstone on the right is the horse from Picasso's "Guernica".
Question: Sally tries to prevent Jack from taking over Christmas using Fog Juice. How will fog stop him?
Answer: Well, it won't. The fog only covered the ground. Because once Jack flew off in his sleigh, he could see. So, it didn't really stop him. He just had to fly above it, and boom! He could see.
Answer: As seen in the movie, the Fog Juice made it difficult to see anything. Sally had hoped that with no way of seeing where he was going, she would be able to stop him from leaving Halloween Town and save his life.