Apparently Mark Hamill didn’t even spoil The Empire Strikes Back for his castmates

Though nowadays even the most basic aspects of a film can be considered spoilers, there were once only a handful of closely held secrets in film canon considered sacrosanct. One of those being (Spoiler alert!) the fact that Darth Vader is Luke’s father. In a recent appearance on The Graham Norton Show, Mark Hamill explained that, from the time they were shooting the film to its eventual premiere, he was one of the few people entrusted to keep that secret from everybody, including his fellow castmates.

“There was a wonderful substitute revelation in that scene, the way we filmed it, Vader said, ‘You don’t know the truth. Obi-wan killed your father,’” said Hamill, adding that the rest of the scene went exactly as we see in the final version. Of course, this was just the cover-up, as George Lucas and director Irvin Kershner had planned to replace the big reveal with an ADR line from James Earl Jones. “I know it, George Lucas knows it, and, when I tell, you’ll know it, but if it leaks, we’ll know it was you,” Kershner told Hamill in his dressing room before handing him a piece of paper that revealed the true fate of Anakin Skywalker.

Now that Hamill was in possession of the greatest twist since audiences met Norman Bates’ mother (again, spoiler), he just had to keep it under wraps for a few more months. Unfortunately, that meant staying tightlipped around his coworkers, especially the late Carrie Fischer. “If you really wanted to get something out fast, you’d ask Carrie to keep it in confidence.” Thankfully, Hamill managed to make it all the way to the premiere without spilling the beans, and everyone was able to experience the film’s climax with fresh eyes. The only person not thrilled by this was Harrison Ford who, as Hamill explains in his pitch-perfect impression, leaned over and said, “Hey kid, you didn’t fucking tell me that.”