McDiarmid and Ray Park, who played Darth Maul in The Phantom Menace, sat down with Warwick Davis to talk about making the first prequel film to mark its 20th anniversary. At the start, Davis asked about McDiarmid's special appearance Friday.
"I just happened to be in the area, so I thought I should just drop in for a laugh," McDiarmid joked.
On Friday, Lucasfilm showed off the first trailer for Star Wars: The Rise of Skywalker, which ended with Palpatine's famous laugh. McDiarmid then made a surprise appearance, calling for the trailer to be run again.
Even after Return of the Jedi, McDiarmid said he thought he would never play Palpatine again. After all, the last time anyone saw the character, he was thrown down a shaft in the second Death Star.
When asked if he thought he would bring Palpatine to life on the screen again, McDiarmid joked, "No, because as you know, Darth Vader chucked me and I thought that was the end."
"I was under the assumption that we'd never see him again," McDiarmid teased later. "I guess that's how it will remain."
He said he repeatedly asked George Lucas if there would be another opportunity to play Palpatine, Lucas repeatedly told him the character was dead. Any time he came up with suggestions to bring the character back, Lucas shot him down. That made getting the call to play Palpatine for the prequels even more surprising.
McDiarmid also explained that he was kept in the dark about Darth Sidious and Senator Palpatine were even the same character during filming. He joked that no one ever told him that, so he had to work it out himself over time.
The Rise of Skywalker will be the first time McDiarmid is playing Palpatine on the big screen since Revenge of the Sith wrapped in 2005. It is still not clear how the character is being brought back to life, but nothing is impossible thanks to the power of the Dark Side. Fans will have to wait for an explanation when the movie hits theaters in December.
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