Read More... Mike Birbiglia, Keegan-Michael Key (Credit: AP/Chris Pizzello) “Don’t Think Twice” is a sly, heartfelt comedy about an improv troupe called The Commune. Its founder, Miles (Mike Birbiglia), once had a shot at being on “Weekend Live,” a national sketch comedy TV show in the “Saturday Night Live” vein. While Miles is still waiting for his big break, two of his colleagues, Sam (Gillian Jacobs) and Jack (Keegan-Michael Key), get an audition for “Weekend Live,” and the tight-knit group starts to splinter. Birbiglia, who wrote and directed the film, knows how to integrate various comedic forms in “Don’t Think Twice,” which relies on sarcasm, satire, physical humor and, yes, improv to give the characters depth as situations challenge them both personally and professionally. But what makes the film so funny — and why it works so well — are the uniformly strong performances.