"The two days that I watched, though, were both little flashbacks -- so she was playing Lucy in the late '30s and mid-'40s. She wasn't Lucy of Lucy Ricardo fame yet, so it was a trifle different," Lucie shared. "And I know she meant it to be, so it could feel different."
"But boy, what she did was astounding," Lucie added. "She's got such poise and class."
Lucie also said that everyone in the film got their roles because of their performance ability more than anything else, explaining, "There are no lookalikes."
"Nobody was cast because they look exactly like somebody. They were cast because they're spectacular performers, actors, and they can capture the basic essence of what has been written in this script," she shared.
Lucie explained that director and screenwriter Aaron Sorkin "was adamant about that," which she's thankful for, and that she's "looking forward to seeing the finished product."
While specific details surrounding the plot of the biopic have been kept largely under wraps, Lucie revealed that a great deal of the story unfolds over the course of one week during the production of her parents' iconic sitcom I Love Lucy in the 1950s.
"It takes place, primarily, during rehearsals for one of the shows. There are a few scenes where they're at their house in Chatsworth, before working, after working," she said. "There are two or three short flashback scenes to her life before I Love Lucy, when she worked on the radio show, when she was trying to convince the network to hire dad."
Lucie cautioned, however, that there are some scenes in which Sorkin took "some theatrical license" and presented things that may not have gone down the way he wrote.
"But stuff happens that week that didn't happen altogether the way Aaron has written it," she said. "But you do learn a lot about what it was like back then. His dialogue is always incredible. And I think he treated my mother and my father really well. I think they are accurate composites of these people."
"What I saw was extraordinarily classy and first rate," she reiterated. "The people that he has cast are just really great performers."
"I think that the people thought that we've cast them as Lucy and Ricky Ricardo," Sorkin told ET's Matt Cohen in February. "We see moments from an episode of I Love Lucy. But mostly they are playing Desi Arnaz and Lucille Ball. And they're going to be fantastic. These are two of the greatest actors ever."
"[I'm used to] people making assumptions about what it is and having an opinion about what it is not only before they've seen it, before we've even made it!" he explains. "You can leverage those expectations by then giving people something that's a lot better than what they thought that they were going to get."
Check out the video below to hear more about the exciting biopic.