13 details you may have missed in 'Unlocked,' Netflix's Korean cell phone thriller

The song is a 1995 cut by the band PiPiBand, which is sometimes romanized as Pippi Band. Later in the film, Na-mi sells one of the band's CD's to Jun-yeong.

A hectic opening montage takes us through Lee Na-mi's life via her phone screen. That includes her secret Instagram account, @kirke_nm, where she posts about trendy food, like mint chocolate konjac jelly, playing into a South Korean food trend that brought mint chocolate flavor to everything from desserts to tteokbokki to fried chicken.

During the montage, we also see Na-mi trying and failing to buy tickets to a baseball game — seats that she later ends up purchasing from Jun-yeong. Na-mi also later negotiates with a potential buyer for her Pippi Band CD, whom she doesn't sell to, planting the seed for Jun-yeong to eventually buy it from her.

And, of course, there's a cheeky Netflix logo included in the montage as well.

Jun-yeong — or rather, the man impersonating Jun-yeong, who we'll continue referring to using that name for simplicity's sake — uses several hashtags on an Instagram post that doesn't appear to be on his account. They include the hashtag #참나물 (#chamnamul), a vegetable that we see plated with the rest of the meal.

Jun-yeong's father Ji-man later visits his son's mother, hoping to find information about their son. When he arrives, he goes through Jun-yeong's texts with his mother, where she asks for his address in order to send him some chamnamul. Later, during a shared meal, Ji-man mentions that chamnamul reminds him of Jun-yeong.

As the film approaches its twist, that Jun-yeong is dead and the film's antagonist has assumed his identity, Ji-man's police chief calls him to ask why "a package your wife sent was found at a victim's home." It's presumably the chamnamul package that she sent, which would also explain why Jun-yeong has it at the beginning of the film.

Na-mi works at Cafe Mizi with her father, and the cast visits the establishment several times throughout the film. It seems to be named after Mizi Film, one of the production studios that made the film and shares a logo with the studio.

After returning Na-mi's phone with the spyware installed, Jun-yeong changes his laptop background to a photo of her smiling.

What's more striking, however, is the row of photos that show smiling young women and dismal photos of them bound and fearful in alternating order.

When Jun-yeong infiltrates Na-mi's apartment, he comes across her old spare phone in a desk drawer.

He presumably installs spyware on it as well, because later in the film, he's able to take control of the same phone after Na-mi switches back to it to avoid him spying on her.

Na-mi loves the plumade that her father makes, but typically doesn't sell due to lack of demand, at the cafe. While the fake Jun-yeong orders plumade from the cafe multiple times, he casts suspicion on the real Jun-yeong by burying his victims near a plum tree that Jun-yeong planted with his family.

Na-mi later tells the fake Jun-yeong that she and her father grow the plums themselves.

Jun-yeong withdraws cash using Eun Mi-gyeong's card, which he crushes after obtaining the money. Later, we learn that Mi-gyeong was likely one of his victims, a woman whose mother believes that Mi-gyeong ran away with to Thailand.

It's possible that Mi-gyeong is the woman whose Instagram account he posts on earlier in the film, when he shares a photo of ramen with the hashtag #ThailandLife and the location set to Chiang Mai, Thailand.

When Ji-man returns to Jun-yeong's apartment, after receiving an unsettling series of texts from the man, he discovers several vials of plant food scattered on the ground. They're the same vials of plant food that were found near the buried bodies, and the same that Jun-yeong's notes reference planting in order to frame the real Jun-yeong for the murders.

There's a shot from above showing Na-mi in a red shirt standing among a moving crowd of people wearing neutral tones. All of them are looking down at their phones.

Later, we see what she wrote, which directly contradicts what she told Ji-man and his partner verbally. While she told them that she would text them to let them know she was alright, her note read, "No texts, only calls."

This becomes critical later on when Jun-yeong forces her to send the police a text, thereby letting them know that she's in trouble.

Ji-man eventually finds his son's cell phone, which the fake Jun-yeong has labeled as number "0," corresponding with the real Jun-yeong's designation in his notes. Other cell phones visible among his belongings bear numbers that presumably correspond to his other victims.

As Na-mi's loaded into an ambulance, a policeman picks up her phone. It displays a text from her friend, who's saved as "Drop-Dead Gorgeous," asking for them to "meet up and talk."