Other mistake: When Lucy asks for an extra piece of candy for her brother during the Trick or Treat scene, her right hand has five fingers when she holds it up, but her left hand only has four fingers.
Other mistake: There is very little drawn correctly about the neighborhood as Lucy and Linus are walking through it in the beginning. There are houses dotted throughout, but all directly on the grass. There's no streets, no sidewalks, no driveways, and most don't even have a garage. However there is one random electric telephone pole they pass.
Continuity mistake: When Linus and Lucy are heading to the pumpkin patch at the beginning of the film, Linus takes his blanket with him, but when they pick up a pumpkin and march back, Linus no longer has his blanket.
Answer: From what I've seen, usually Sally is often annoying Linus with her flirting when he has nothing in common with her, or he's just trying to do something to help her and she tries to make it into more. Here, Sally's comments make Linus think she believes in the Great Pumpkin too, or is at least interested in hearing more about it. It's more that he's excited she likes the same thing as he does. Later in the pumpkin patch, he's happy she's there because he wants to share the experience with someone, not because he has any feeling towards Sally.
Bishop73