In addition to giving a spiky and compelling performance as Rickey, the film’s equivalent of the Kieran Culkin fast-talking-bearded-charmer-with-sociopath-tendencies in “A Real Pain,” Michael Angarano also directed the movie, from a script he cowrote with the documentary veteran Chris Smith. And Angarano proves a confident and vivacious filmmaker, though in an engagingly scruffy and almost random way.