At the scene of the first shooting, the place where the victim's body fell is outlined with chalk. This is a myth about murder investigations. A victim's body is never outlined with chalk (or anything else) because that would contaminate the crime scene, and photographing the body, which is a routine part of such investigations, makes an outline on the ground irrelevant in any event.
In the second shooting, the unsub fires two shots. Immediately after each shot, the spent shells falls. However, the rifle the unsub was using, the L115, is a bolt-action rifle that requires a chamber cycle to fire again (this is demonstrated in most of the "assembly" scenes), making this an impossibility.