During Disney Investor Day in 2020, Marvel Studios President Kevin Feige surprised everyone when he officially announced Newton's casting as Cassie for Ant-Man 3, taking over the role from Emma Furhmann in Avengers: Endgame.
Ant-Man 3 director Peyton Reed subtly explained the recast, noting that time is the central focus of the threequel, and a good chunk of it has to do with Cassie's transition into an adult and Scott pondering with how much time he's lost with her.
Why Did Marvel Recast Cassie Lang?
Avengers: Endgame then introduced a brand new actress to portray Cassie due to the in-universe five-year time jump from Avengers: Infinity War. There, Emma Furhmann played the character in a brief yet emotional sequence with Paul Rudd's Scott Lang.
In the threequel, Kathryn Newton took over the role of Cassie.
As explained during the audio commentary for Ant-Man and The Wasp: Quantumania, director Peyton Reed admitted that an actress of Newton's caliber needed to be hired so that they could "really hang with Paul Rudd and sort of not be left in the dust" in the sequel:
“We’ve just introduced our now 18-year-old Cassie Lang. Kathryn Newton, of course, an actor who I have admired for a long time. And when we were talking about Cassie in this movie, she’s aged five years since the events of 'Ant-Man and The Wasp.' And I wanted someone in that role who could really hang with Paul Rudd and sort of not be left in the dust."
The actress playing Cassie Lang in Quantumania needed to be "sharp, and quick, and funny," all traits which Newton possessed, according to Reed:
"She’s gotta be sharp, and quick, and funny. And also, [Newton] is an athlete. She’s a world-class golfer. She has the physicality for the role.”
Ant-Man 3 writer Jeff Loveness chimed in, saying that Newton has a "bit of that sense of humor" and "a bit of that messy quality" from Rudd's Scott Lang:
“And just someone who can seem like Scott Lang’s daughter. You know, what does she pick up from him? What does she go against? She’s got the heart of Scott. She’s also got a bit of that sense of humor, a bit of that messy quality.”
The Ant-Man director then offered high praise for Fortson's portrayal of Cassie, pointing out that she has such "a winning personality:"
“It’s a tricky thing, because Abby Ryder Fortson, who plays six-year-old and then nine-year-old Cassie in the first two movies, is such a winning personality."
Reed also further explained why 18-year-old Cassie is a completely different character due to her having "ideas of her own now:"
"And… now that you’re with 18-year-old Cassie, you had to really like the idea, ‘Oh, wow! She grew up into this person.’ Cassie has ideas of her own now. She’s an ideality and she has some different ideas than her dad about what it might take to be a hero and what justice means in the world.”
When Will Kathryn Newton’s Cassie Lang Return?
At this stage, it is unknown when Kathryn Newton's Cassie Lang will return to the MCU. Whether it is a potential Young Avengers project or Avengers: The Kang Dynasty, Ant-Man 3's happy ending indicated that the character is prime for a comeback sooner rather than later.
While it's unfortunate that Emma Furhmann didn't return as Cassie Lang, Kathryn Newton proved that she is perfect for the role in Ant-Man and The Wasp: Quantumania.
Peyton Reed's comments about Newton being able to "hang" with Paul Rudd in the MCU threequel make sense since the father-and-daughter chemistry between Cassie and Scott has been the bread and butter of the Ant-Man movies.
In fact, Rudd already gave Newton the best advice upon entering the MCU when he told her not to ever “hold back,” and how she “[shouldn’t] finish this movie and wish that [she] didn’t try that joke."
Although recasting is challenging for all the parties involved, Newton's casting in Ant-Man 3 further solidified that Marvel Studios will do whatever it takes to cast the perfect actor for the role.
Ant-Man and The Wasp: Quantumania is available to purchase on all major digital platforms.