The Flash, “Into the Speed Force:” The Flash heads into the Speed Force to save Wally, as he and the rest of the team confront seemingly arbitrary rules of reality designed to force drama, and H.R. continues to be annoying.

Legends of Tomorrow, “Moonshot:” Houston, we have a problem.

Arrow, “Checkmate”: Ollie learns more about Prometheus and, rock-star-like, he trashes the Arrowcave. The ep also features a shoot-out at a hockey arena, but of the deadly variety.