Lee’s comment that it is World War III is clearly meant to be sarcastic, but there is some truth to his words. They
are completely isolated in Hell, and they
wouldn’t know if something awful happened back home. This conversation also speaks to the group’s inexperience and naivety, because it is highly unlikely that any local festival would involve hundreds of jets. The cost would be too great, and it would involve too much man power. The planes are definitely not part of a friendly demonstration, but Ellie and the others don’t realize this.