"I wish I never cut my hair the way I did," Katie Leung told PEOPLE on Friday at Universal Orlando's three-day Celebration of Harry Potter event.
"I had this horrific haircut!" she said of her look as the shy Ravenclaw in 2007's Harry Potter and the Order of the Phoenix.
But that's not the only thing she would change about her run in the Potter series.
"You grow as an actor and you change your choices," she says of shooting the decade-long series. "That's partly why I can't watch them. I'm just really judgmental of myself."
Leung, who first appeared as Cho in 2005's Harry Potter and the Goblet of Fire, says that as a young actor, nothing could have prepared her for the breadth of the production.
"I remember being on set on the first day and being completely overwhelmed by how many people were involved," she says. "Just not having an idea of what it was like to be on a film set. I remember being really nervous and scared on the first day and consequently for another few months!"
Bonnie Wright, who was just 10 when she debuted as Harry's true love Ginny Weasley in 2001's Harry Potter and the Sorcerer's Stone, says that even if she could give her younger self advice now, she wouldn't.
"The idea of the unknown made it that much more special," she says. "Being so young and being innocent about it enabled everything to be quite new. I think for all of us, we were all in the same boat. None of us really knew where it was going to head. The unknown to that was quite beautiful in a way."
Other Potter alums attending A Celebration of Harry Potter at Universal Orlando's Wizarding World of Harry Potter," >Wizarding World, which runs through January 31, include Rupert Grint, Evanna Lynch and Matthew Lewis.
Wright posted a picture of herself alongside Leung and Lynch, wearing bracelets Harry Potter-themed bracelets gifted to them by J.K. Rowling.
"Thank you @jk_rowling for our @lumos bracelets," she captioned the snapshot.
West coast fans may be soon getting their own chance to enter the Potter world as Universal Studios is opening a themed park in their Los Angeles location.