During the sequence when Detective Cross holds up the photos of 2 of the murdered women, she has one in each hand and is holding them up, showing them to Vincent. She drops the one in her right hand and holds up the one in her left, saying "Tell me about the intimacy you shared with this one, while you stuck a knife through her temple". The photo she is holding is of a woman with a broken neck. The one with the stab wounds is no longer in her hand.
At the opening of the film, Vincent, in response to being asked why he kills women, responds: "Why? Why do tigers eat zebra? Why do we make war on weaker nations? It's simply the way the world works, Detective Cross." The only problem is that tigers don't eat zebra. They don't even live on the same continent.