Well, there is a twist. Shamaylan's twists are usually geared around the sudden change of perception. You saw things which your mind may have momentarily questioned, but then you went on. Once hit with the twist, you wonder how you missed it. This was true in The Sixth Sense, Unbreakable, and The Village. Signs didn't really have a twist - that was more like a case of serendipity. Still, even then, all those water glasses were similarly placed in full view and quickly ignored by most of us.