Barry Allen and Oliver Queen have traded places in this new trailer for ‘Elseworlds‘, the upcoming Arrowverse crossover event:  ‘Elseworlds‘ stars Grant Gustin, Stephen Amell, Candice Patton, Danielle Panabaker, Carlos Valdes, David Ramsey, Emily Bett Rickards, Echo Kellum, Melissa Benoist, Mehcad Brooks, Chyler Leigh, Tyler Hoechlin and Bob Frazer, with guest stars Ruby Rose,