Bradbury, Ray. The Halloween Tree. (1993)
This is the cartoon movie version of Ray Bradbury's short-story of the same name. Directed by Mario Piluso who helped bring many of the best comics of the 1980s it tells the story of four friends who race through time to save their friend Pip's soul on Halloween night. The movie doesn't stray very far from Bradbury's original short story, so if you've read it there won't be very many surprises. What the movie does well is evoke the spookiness and sense of anything-is-possible that comes from the night when children roam the streets trick or treating and the spirits of the dead might just be out there alongside them.
The best parts of the movie are Ray Bradbury's narration and the fact that Leonard Nimoy does the voice of Moundshround. Unfortunately this movie is not available to buy on DVD and hard to find on VHS. You can, however, watch it on YouTube.
Of course, you could always just read the short-story. :)