Yeah, the sparkle is the rain... I'm 99% sure. I think they're just extra large clear umbrellas. A lot of the people in the front of the crowd were given the same ones, and when you look at them dry, they don't appear to sparkle.
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I'm pretty sure they wouldn't (especially the males) all be carrying clear sparkly umbrellas... just find an extra large umbrella in clear; you could probably find one at Walmart or Target.