I've got some people trapped in a building in a forest surrounded by zombies. They're thinking about setting the forest on fire, and then it starts to rain. Oh well.
A fella suggested that I make a bigger deal out of their attempt to set the forest on fire. It would be a way to go. But I don't think the audience is going to really believe that they're going to succeed. 'Cause there's going to be no conflagration in the trailer or the poster -- which there would be if the movie had a forest fire. So the audience would be ahead of the characters waiting for them to get back to the exciting parts of the plot.
Instead I went for the gag -- pretty much the moment they think of setting the forest on fire, it starts to rain. Wayyy ahead of you, audience.
You want to be constantly aware of what the audience is expecting. Thwart them on plot details -- surprise them with how things turn out.
On the other hand, satisfy their expectations on emotions -- give them the ending they're expecting emotionally. Most of our characters survive the zombies. If they didn't, it would be a dark, dark movie (like Night of the Living Dead
), and this is a horror comedy.
In particular, be aware of how much the audience is going to know from the trailers on TV, or the DVD box text.
Scorsese remarked that Raging Bull
starts with a fat Robert De Niro partly because he knew the audience would have read about how De Niro gained a ton of weight to play the aging Jake La Motta. He knew the audience would be waiting to see the "fat man." They'd be distracted until they got to see Robert De Niro fat. So he gave them the fat man right out of the box so that they wouldn't be distracted.
Managing audience expectations is a big part of telling stories on screen. It's really the essence of storytelling. So always think of your audience -- picture them in your mind -- as you craft the story.