“Fifty-One” (05.04, 2012) Written by Sam Catlin (Previous Episodes: “Down,” “4 Days Out,” “Green Light,” “Fly,” “Half Measures,” “Open House,” “Hermanos,” and “Crawl Space”) Directed by Rian Johnson (Previous Episodes: “Fly”)   It’s not every TV show that can get the best film director working today to direct a few episodes. In fact, it’s exactly…