I think you a really on to something here. Police decoys could be carrying items in which are hidden small dye packs, much like the ones hidden in money handed over to bank robbers.
Or if one was concerned about possible collateral damage from a wayward explosion the size, say, of a cherrybomb (would produce a goodly little bruise, minimally, or a small flesh wound tucked into a butt pocket....then one could use flash-paper printed money and enhance with a smoke chemical. Would definitely “out” the perp and produce a small ass-burn without any animals being harmed during the shooting of this film.