Oscar Isaac had a scene with Carrie Fisher in "Star Wars: The Last Jedi" he'll never forget -- because she slapped him 27 times!

Stopping by "The Late Show with Stephen Colbert" last night (which also happened to be the 40th anniversary of "Star Wars"), Isaac shared this anecdote.

"A large amount of the stuff I got to do was with Carrie, which was amazing," Isaac told Colbert. "I remember the first day of shooting was a scene with Carrie ... I remember it was a scene where I come up and talk with her, and she is very upset with me and slaps me. And Rian Johnson, the director, kept doing it over and over. I think it ended up being 27 takes of Carrie just leaning in [to slap me] and every time she did a different spot on my face.

He remembered the late icon, saying, "She was, by far, one of the quickest-witted, funniest, most down-to-earth, real human beings, I ever had the opportunity of working with. She does amazing work in this. It was definitely a heartbreaker [to lose her]."

He also recalled seeing his first "Star Wars" film at age 4: "Return of the Jedi" (although he's unclear about what year it came out. It was 1983, Oscar!). The most memorable moment: When Darth Vader's helmet is briefly off and we see that he's just "an old, bald, fat dude."

The actor also mentioned that he tried to keep his "Force Awakens" script after the film was finished, and that Disney lawyers finally had to ask for it back! Fortunately, after the film opened, he got a very fancy of the version of the script sent to him, "this leather-bound thing with my name on it." Nice!