“Olympics” (8 p.m., NBC): Track finals play out with the women’s 400 meters and

“Olympics” (8 p.m., NBC): Track finals play out with the women’s 400 meters and the men’s 200 meters.

“Mythbusters” (9 p.m., Discovery): Tonight’s edition of “Mythbusters” includes ninja myths, including the concept of catching an arrow in midair and knocking out a foe with a punch from an inch away. Way cool.