In a new interview with Emmy-winner Jake Hamilton, writer-director James Gunn dives deep into the making of Superman, and yes, the briefs are a big deal.

From teasing that David Corenswet’s Man of Steel may have already met Batman to breaking down why Nicholas Hoult became Lex Luthor instead of Clark Kent, Gunn shares insights that every DC fan will want to hear. He also talks about bringing Christopher Reeve’s legacy to set with a cameo by his son Will, and finding the perfect chemistry between Superman and Lois (Rachel Brosnahan).

And yes, Gunn confirms it: Superman’s briefs were the most controversial thing on set.

Watch the full interview to hear Gunn talk about Crypto the Superdog, John Williams’ iconic score, and how he hopes Jerry Siegel and Joe Shuster (the creators of Superman) would feel about the film.