Especialy if you make your own flares (like Bengal Lights, they are blue). The red color and struntium emission lines are a giveaway if you use highway flares, though in one instance an expert looked at the photos and declared that the colour was not of this Earth.
Taping mylar strips to the baloon is nice, too.
Not that I’ve done either, mind you.
of course you haven’t! I wonder how elaborate you can make it before you’d get arrested? Dropping fifty pounds of shredded aluminum foil to fool radars might do that.