During the ending when Bonnie gets shot, we see her get sprayed with tommy-gun bullets. During the slo-mo scene, she is alternately covered with bullet holes that are bloody, and then in the next camera shot they are not bloody, and then bloody, and then not bloody.
The reason that there is no blood is because this scene was very violent as it was for the times, and the added blood would have made all the more risky than it was... that was kind of an incoherent sentence, but whatever....