One of the most unforgettable scenes in Wicked finds Elphaba hopping an enormous emerald green train to Oz, where she has been summoned by the Wizard. Just as the train begins to depart, she invites Galinda to also join. The massive locomotive is visually stunning, helping to sell the importance of the moment between the characters.

Instead of using CGI to create that train, the production built a real one. The finished product was impressively huge. It weighed 16 tons and took two days to move into place for the sequence. The result was worth it, creating one of the most indelible cinematic images of the year.

When you think of Wicked onstage, it’s impossible not to think of Kristen Chenoweth and Idina Menzel who, respectively, portrayed Galinda and Elphaba in the Broadway production. The actresses are so closely associated with the show that the movie’s director, producers, and stars all agreed they needed to make a cameo appearance. The question was how to fit them in substantively and respectfully.

Composer/lyricist Stephen Schwartz came up with the idea to extend the Wiz-O-Mania sequence in the song “One Short Day” to give Chenoweth and Menzel a decent-sized musical number of their own. The ladies portray enchantresses of Oz who relay the story of the Grimmerie, a magical tome at the heart of the story. The sequence gave them something noteworthy to do, as opposed to simply making a stunt cameo. Said director Jon M. Chu:

The fact that they were the wise women of Oz felt so great. And then on top of that, there’s this theater group in Emerald City and the idea that they were the biggest stars in Emerald City was so fun. We love paying homage to them in there.

CGI can produce all kinds of amazing images, but at some level, audiences still realize what they’re seeing isn’t real. That can have an unintended psychological impact. Wicked director Jon M. Chu and production designer Nathan Crowley wanted something better for the opening of the movie, which takes place in a field of colorful tulips.

To achieve the effect, the filmmakers consulted with a flower farmer who agreed to provide the production with a whopping nine million tulip bulbs for use onscreen. The flowers needed to be shipped from the Netherlands and planted immediately before the ground started to freeze. They helped to create a breathtaking image that makes audiences swoon. The effort was worth it, according to Crowley, who said:

For me, the cinema is about being taken away on a journey. And when the CGI is too much and the set build is too little, it stops me from falling into the film. Here, the actors are running through actual flower fields, and you see the blooms move in the wind. It feels organic.

For movie musicals, the songs are typically pre-recorded in advance and the actors lip sync to those tracks when the cameras roll. This is done so they can focus on their performances without worrying about whether or not they’re in pitch. Cynthia Erivo and Ariana Grande are both extremely accomplished vocalists, though, so they made the atypical decision to sing their vocals live during production.

Even in the most uncomfortable moments, the stars stuck to their decision. During the shooting of the song “Defying Gravity,” Erivo sang live despite having “a harness pulling and pushing and yanking and tugging on every nook and cranny that there is.”

On the stage, Wicked runs about two hours and 45 minutes. Wicked: Part 1 is roughly that same length, and it’s presumed the second part will be similarly long. The choice to split the musical into two movies may therefore seem puzzling to fans and newcomers alike.

There are two reasons behind the decision, according to composer/lyricist Stephen Schwartz. The first was a desire to avoid “cutting or omitting things that we wanted to include and that we think fans of the show and the story will appreciate.”

The second, bigger reason had to do with Wicked‘s signature number, “Defying Gravity,” which ends the first act in show-stopping form. According to Schwartz:

We found it very difficult to get past ‘Defying Gravity’ without a break. That song is written specifically to bring a curtain down, and whatever scene to follow it without a break just seemed hugely anti-climactic.

Before Wicked, Ariana Grande was an internationally renowned pop singer. She also had television acting experience as one of the stars of the Nickelodeon sitcom Sam & Cat. She had not, however, headlined a major motion picture before. That made her casting a slightly risky bet. She had the singing chops, but could she carry a picture? That was the question Jon M. Chu kept asking himself.

As a result, Grande ended up auditioning five times before finally landing the role of Galinda. Of those five auditions, Chu said:

She came in five times for us. Every time, she was the most interesting person in the room. I resisted. I was like, ‘There’s no way Ariana Grande, the person we think of, can handle this, carrying a movie, her first movie.

By the end of that fifth audition, any lingering doubts were erased in the director’s mind and his Galinda was found. Incidentally, other actresses who auditioned for the role include Amanda Seyfried, Dove Cameron, and Renee Rapp.

Moviegoers notice something unexpected when Wicked gets to its end credits. Pop superstar Ariana Grande is billed onscreen as “Ariana Grande-Butera.” Given that she’s been a household name for years, some might wonder where the “Butera” came from.

The answer is deeply personal. Having professionally shortened her name due to a long-time estrangement from her father, Edward Butera, she felt the film represented a chance to return to her roots. The star explained that Grande-Butera “was my name when I went to see [Wicked on stage] when I was 10 years old, and it felt like a really lovely way of honoring that.”

Father and daughter eventually reunited, helping to pave the way for her onscreen billing. In fact, she showed him the end credit billing in advance of the movie’s release, saying:

I pulled it up in my laptop, and I recorded him secretly, and I told him I wanted to show him the typography of the credits because he is a graphic designer. He loves that stuff. And anyway, it was a big surprise, and he cried. It was very emotional.”

A very prominent scene in Wicked features the presentation of a pair of ruby slippers. They obviously indicate a connection to the character of Dorothy from The Wizard of Oz. Viewers may scratch their heads during the sequence, though, because the shoes are not red. How can a Wizard of Oz-related movie not have the red shoes?

The answer has to do with rights issues. Wicked is released by Universal Pictures, but MGM maintains the rights to many elements from The Wizard of Oz, including those red ruby slippers. Including them could have led to a lawsuit. To get around the matter, the filmmakers returned to L. Frank Baum’s original book, in which Dorothy’s slippers are silver.

On a related note, the shape of the yellow brick road was also under MGM’s domain, meaning Wicked couldn’t replicate its famous spiral.

Wicked presented a very specific challenge for cinematographer Alice Brooks. The two main characters have intentionally opposing looks. Galinda is fair-skinned, blonde, and usually clad in some shade of pink. Elphaba is green, dark haired, and primarily dressed in black. Figuring out how to light both characters in a manner that would make them look equally good was a complex task.

This could have been easily taken care of via color correction during the film’s post-production, but Brooks didn’t want to do that. She explained:

I really wanted it all to be in camera, with all the details of their costumes and makeup too. It took a long time to figure it out [with our other departments] so that they could both be in the same frame and both look equally as gorgeous.

Saturday Night Live cast member Bowen Yang has a supporting role as Pfannee, one of Glinda’s sycophantic friends. The actor has long been obsessed with the musical, making it a dream come true to be part of the film adaptation.

Yang credits his parents, saying he believes they manifested both his appearance in Wicked and his success on SNL. The actor explained:

My first trip to New York when I was 13, Wicked had just come out, but I begged my parents to go to the Gershwin just so I could touch the glass and look inside the lobby. We couldn’t afford tickets, but I just wanted to feel it in my hand, just look at the signs. And then, that same day, we went to 30 Rock at NBC and did the studio tour, and I sat in the seats at SNL. So, I was like, ‘If those two things happened on the same day, I need them to intersect just one more time.’