14 hidden details you might have missed in 'Promising Young Woman'

According to hair director Daniel Curet, Cassie would adopt the aesthetics of women she knew had been in similar situations.

The movie opens with one of Cassie's "hits" at a nightclub, where she's dressed up in stereotypical "business casual" clothes.

Cassie looks completely drunk, and gets picked up by a nice-enough seeming guy. But when that guy (played by "The OC" darling Adam Brody) takes her home and starts undressing her against her will, Cassie sits up and reveals that she's stone-cold sober.

The revelation is meant to be a surprise both to the man in the process of assaulting her, but also for the audience.

"It needed to look real, obviously," Wells said. "So the makeup was more natural; basically what a professional woman would wear. But in order to help create the effect of her being inebriated, I sprayed her face with a little Avion to give some sheen."

Wells stayed away from a standard blush for Cassie's makeup. Instead she used a stain, and "stippled it on in an uneven fashion so it would ... look like she had too much to drink."

"By the time she sits up on the bed and says to him, 'What are you doing?' ... it's like a frightening mess," Wells said. " I wanted that to be a bit frightening and jarring because I remember thinking when I read that part of the script, 'Oh, we're in for a great ride. This is totally not what I thought it was going to be.'"

After this first "hit," we see Cassie at her day job inside a pastel-laden coffee shop.

"With that version of Cassie, I wanted her to be completely different than any of the personas or disguises that she takes on for her hits," Wells said. "I really wanted it to be like a normal, natural person."

Wells used really soft colors for her lip and eyes, shades of rose and mauve that went well with Mulligan's face and also matched the "candy color" palette of the whole movie.

"Even regular Cassie is sort of in a disguise, because she's really very sad and angry," Wells said. "But we didn't want her regular everyday makeup to reflect that [part of her]."

Wells also says she gave Mulligan a "really soft spray tan" for the movie, to deepen her naturally fair complexion "just a little bit" for the more sun-kissed role of Cassie.

Whenever Cassie is seen working at the coffee shop, or out in the world as her "normal" self, her hair is almost always down and in long, beachy waves.

"I insisted on putting like 10 pounds of hair on her," Curet said. "It was a double taping hair extension — there was extra, extra hair, much more so than an ordinary person would come to the salon to get."

"We hit on this Brigitte Bardot period-esque look with the heavy fringe," he continued. "On some levels, the women I've known my entire life hide behind their hair. I really wanted to arm Cassandra with a ton of hair."

"It looks good and it's luscious and everything, but then it also served our purpose," he continued. "It's arming and disarming at the same time."

The next time we see Cassie preparing for a hit, she watches a video makeup tutorial for "blowjob lips." The makeup artist vlogger is played by Emerald Fennell in a small cameo moment.

Wells wanted her makeup "to look a little bit hard, but also to reflect a bit of the sadness."

Instead of the standard winged eyeliner that's in fashion now, Cassie's eye makeup turned a bit down before curving upwards.

"It creates this sad, downtrodden eye look," Wells said. "And it's very subtle, but when she wipes that lipstick away, it almost looks a little bit like the Joker."

"It's like the tears of a clown," Wells continued. "Like, 'On the outside, I feel really strong and like I'm just living a normal life, but on the inside, I'm in a lot of pain and I'm angry.'"

The colored and feathered hair extensions were meant to play into Cassie's new persona for the night.

For this hit, the audience doesn't see the bar or club where Cassie gets picked up, but Curet said you can infer what kind of location she visited based on how she's dressing and the way the man with her is acting.

"This guy is talking all this blithering nonsense about his book, and you could tell that she picked him up at some hipster kind of dive bar," Curet said. "The hippie feathers-thing in her hair just felt like 'Oh my God, this is hilarious. Let's do it.'"

Variety published a copy of Fennell's "Promising Young Woman" script in January, and in the scene shown above Cassie is described as "on edge, dressed like a cut-price Kardashian."

Curet and Wells took their cues from that scene description, giving Cassie a high ponytail with more extensions than usual and "way too much" makeup, as if Cassie had watched a YouTube tutorial on the Kardashian-style contouring and tried to recreate it.

"[The Kardashians'] makeup is usually blended nicely, but I wanted that reference of 'a bit too much,'" Wells said, adding that she wanted it to look like Cassie had done it herself.

Wells made Mulligan's face look more angular than usual with the makeup, conveying the harshness her character was feeling in this scene. By the end of the sequence, Cassie runs into her new boyfriend (Ryan, played by Bo Burnham), and feels like she's been caught in her disguise.

"That's the only time [in the movie] that she's not wearing heavy fringe," Curet said. "I wanted her to be completely exposed."

Cassie confronts Mr. Green (played by Alfred Molina) — the man who helped Al Monroe avoid prosecution for his assault on Cassie's best friend Nina.

Of all the people Cassie seeks revenge upon throughout "Promising Young Woman," Mr. Green is the only one who apologizes for his actions. He expresses remorse and Cassie forgives him.

Curet told Insider that this emotional catharsis is part of the reason why Cassie's aesthetic in this scene was referred to as the "Virgin Mary."

"It came from the emotional tone of this scene, because of the redemption for Alfred Molina's character," Curet said also noting that Carrie wore a "pale blue dress and Virgin Mary's mantle is blue."

Wells gave Cassie the most toned-down makeup look possible for this scene that was "really soft," she said.

"Everything was pretty nude, but I did use a really soft shimmer on her eyes that actually had a little bit of glitter in it," Wells said.

Throughout their relationship, Cassie wears lots of pinks and other bright colors to their dates. But when she finds out that Ryan had been at the party where Nina was assaulted, and watched as the attack happened, she's back wearing a blue, flowy dress that's reminiscent of the scene with Mr. Green.

By keeping her "soft and sweet looking" for her confrontation of Ryan, Wells said it "differentiated [that moment] fromt the type of anger that she was feeling when she makes the hits."

"She was going to go tell somebody who she was falling in love with like, 'You're a creep. I just discovered that you actually were part of this whole mess,'" Wells said. "And I'm telling you as the woman who is in love with you."

But unlike Mr. Green, Ryan's immediate reaction to Cassie is defensive — he doesn't apologize or take responsibility for his complicity. And so Cassie blackmails Ryan into telling her the location of Al Monroe's bachelor party, finally caving into her anger.

The multi-colored hair piece was originally written in Fennell's script as a "powder blue" wig, but it wound up being a mixture of all the same bright hues you see throughout earlier scenes in the movie.

Curet pointed out how Cassie's light blonde hair in the rest of the movie was usually contrasted by her candy-colored wardrobe and the bright set designs. But for this final look, she's wearing mostly white and all the color is concentrated in her wig.

Getting that wig together was "a process," Curet said. He didn't like the first wig option presented because it didn't have bangs. So he "married" together two different wigs.

Curet said it was just him and Mulligan in the costuming trailer for the final fitting, and she told him she wanted the wig cut to an exact length she had in mind.

"So I took razorblades to it, and then paper scissors, and cut it," Curet said. "Then we restyled it so it had a whole new wavy texture."

The script called for "super heightened" makeup, and Wells was up to the challenge.

"I had so much fun with this one," Wells said, reflecting on Cassie's final makeup look. "When I saw the costume and thought about what she was going to be doing, I thought of an evil blow-up doll."

"I lined her lower lid quite a bit beneath her lash line, so that it creates the illusion of this much rounder, bigger eye," Wells added.

She even placed fake eyelashes lashes lower than normal on the bottom half of Mulligan's eyes.

And then to make the whites of her eyes look bigger, Wells used a trick by putting a flesh tone concealer around the bottom of Mulligan's eyes (above the false eyelashes) instead of drawing eyeliner inside of her eye.

"And then with the lips, we of course overdrew them," Wells said. "We went slightly outside of her lip line, but I didn't want her to look cartoonish. I wanted it to be realistic, but still like, 'Oh wow, this is kind of intense.'"

"I did not want a red lip," Wells said. "Everybody uses a red lip for when [the scene is] sexy."

Instead, Wells drew inspiration from the wig's pink and blue colors and selected a "really strong pink" that would keep Cassie's face looking doll-like.

"I made her face really bright," Wells said. "I didn't use a lot of blush because I really wanted the focus to be on eyes and lips. That's where we see people's emotions — in a smile or an expression of the mouth and the eyes so I wanted that to be the focus."

Wells wanted Cassie to look "sexy, but a little bit dark."

"That big eye, when you do it with sort of dark eyeliner around it, it takes on almost a bit of a 'Chucky feeling to it — really wide, kind of scary eyes," Wells said. "That scene where she's standing at the edge of the bed with that blade looking at Al, she looks like she might actually hurt him."

Which was, of course, Cassie's goal: To finally physically harm Nina's assailant. But those who have seen "Promising Young Woman" know that Cassie's final act of vengeance only ended in tragedy.