The railroad "Cassandra Crossing" scene over the Gunnison certainly can stimulate debate. True, Ayn Rand insisted that "second handers" mooch off of those who take risks to produce. But the "risk" needs to be understood in various contexts. In a real world, a train like that wouldn't be run over a new bridge without extensive testing by engineers, some of whom would have to be introverted to do their jobs right. (That's like IT work.) And the new rails had to be laid still by a lot of manual labor (that fascinated my own father's moral sense). Dagney says her workers "volunteered" for the train ride; she had never "harmed" anyone. That's a loaded proposition.
Update: April 30
Richard Sincere has an interesting take on the film in the Charlottesville Libertarian Examiner, here.