In 1987 Elaine May’s comedy “Ishtar” was savaged by critics and flopped spectacularly, but it turns out that the movie is actually pretty funny — and the reason it failed is pretty complicated. Beanie Feldstein and Kaitlyn Dever, the stars of “Booksmart,” tell Kurt Andersen about how they became friends after they were cast as friends — and they bring a playlist of some of their favorite on-screen friendships. The final episode of the original “Star Trek” series aired 50 years ago this week, and Ronald D. Moore reveals how watching reruns of the show made him a science-fiction fan and ultimately led to his job as a staff writer for “Star Trek: The Next Generation.”