Director Danny Boyle and star Ewan McGregor hopped on stage at an absolutely jammed Alamo Drafthouse Ritz on Sunday night to host the (not quite secret) SXSW secret screening of Boyle’s “T2 Trainspotting,” the sequel to the groundbreaking 1996 film.

The movie itself was an emotional wipeout, a kinetic snapshot of iconic characters 20 years on: Mark Renton (in Amsterdam for lo these many years), Sick Boy (now a pimp known by his given name, Simon), Franco Begbie (in prison for a looong time) and Spud Murphy, who still struggles with his addictions.

When Renton returns to Edinburgh for the first time in decades, it is time to look up old flames and settle some scores.

Then again, as Boyle noted in the Q&A afterward, moderated by Austin director Richard Linklater (who has been all over the place this SXSW), the movie is mostly about “how badly men age.

“Women age much more sensibly,” Boyle said. Men just sort of hang on to things, and when they hit middle-age, they start spending a whole lot of time looking back and only vaguely looking ahead at what’s next, he said.

Boyle also noted how “bizarre” it was to see these four actors (McGregor, Jonny Lee Miller, Ewen Bremner and Robert Carlyle) click back into character and chemistry.

McGregor noted that he started work on the film about a week after everyone else and since the film’s mantra was, as Boyle put it, “This better not be (expletive),” McGregor was nervous that he wasn’t going to lock in to Renton.

But he ran into Bremner (Spud) at a meal break, who told him not worry, that once he got on set, Renton would be “right there.” Which he was.

If there is one theme to the film, Boyle said, it’s that “time doesn’t care about you.”