Though set in 1987, Precious is clearly riding a subway from 2005 or later with her son. The yellow and orange bucket scenes have been in subway cars for a while, but the dark floor seen in the movie was a change made to some cars in the late 1990s. Prior, it was a light to medium tan. Also, a sign that warns "Riding or moving between cars is prohibited unless there is an emergency or as directed by police or train crew" is a relatively new sign. Moving between cars has been illegal only since December, 2005.
There are several anachronisms related to the use of computers given the film's setting in 1987: The computer screen on the desk of the secretary at Precious's original school is shown displaying graphical capabilities several years ahead of the film's established time period; the computer on Mariah Carey's desk has a model of CD-ROM installed it which wouldn't be available for another six or seven years; The overall ubiquity of computers on the desks of virtually every educator and social worker as shown in the film would not have been the case in 1987.
Twenty minutes into the movie Precious encounters some rowdy boys hanging out on the street. They are listening to Queen Latifah's "Come Into My House", but that song was not released until 1989. The movie is set in 1987.
In the last scene that features Mariah Carey's character speaking with Monique and Gabourey's character, Mariah begins to tear up. As she tears up, she wipes the tears from her eyes and she's holding what looks like a BIC grip pens, which were not being manufactured in the '80s.
While Precious is holding her baby standing outside a church in the snow, she peers threw the window as the choir sing Soul Holidays " A hit from Gospel group Sounds of Blackness". Though the movie is based in 1987, this song wasn't recorded until October 16,1992.
Rhonda writes a "Do Now" on the board when she takes over the lesson for Ms. Rain. This was NOT part of the Balanced Literacy, an educational movement for English Language Arts classes in 1987 (the year the movie is set). A "Do Now" HAS been utilized in the modified version of the Balanced Literacy model, called the Workshop Model. The Workshop Model is now the instructional model taught to teachers and encouraged in many New York City public schools.
When Precious's teacher is ringing the buzzer, Mary is watching "227." (No footage is shown, but dialogue can be heard.) The dialogue, mainly between Mary and Sandra, is from the episode "A Funny Thing Happened on the Way to the Pageant" (originally aired 29 October 1988).
When Precious steals the fried chicken, she runs out of the restaurant leaving her Each One Teach One notebook behind. The very next scene shows her finishing the chicken and going to class - where they all write in their Each One Teach One notebooks.
When Precious's schoolmates visit her at the hospital, there is a shot of the window with a lady lying in the next bed. The shot breaks away for a second, then back, and the other patient has disappeared.
During the scene where Mariah Carey's character attempts to bring together Precious and her mom Mary, you see the front of Mariah's pocketbook. A few minutes later, when the camera pans back and forth, you see the back of Mariah's pocketbook (the purse changes positions).
When Mary is holding Mongo before the social worker comes in, Mongo is holding a sucker, however, when the social worker is asking Mary about how her job search is going, Mongo is holding a piece of red licorice which she throws on the floor.
Toward the end of the movie, in the scene with Mrs. Weiss (the social worker), Mary and Precious, Mary is wearing a black head-scarf which is tied in the front. At the start of the scene Mary is speaking and only one of the head-scarf tie-tails is visible (the other is tucked in). As we cut away to one of the other women and then back to Mary, the one tie-tail is no longer tucked in... it's now un-tucked and both are visibly flopping around in front of Mary's forehead. Later in the scene the un-tucked tie-tail is again tucked back in and only one is visibly out.
When Ms Rain is trying to evaluate Precious' reading skills, and Precious doesn't respond, Ms Rain says, "I'm gonna call the nurse." We should see her in full motion, but Ms Rain gets up and immediately sits back down within two frames. There's a split second, yet obvious changeover/cut.
Precious and her principal are talking back and forth through the apartment intercom system, but Precious is still able to hear the first several words of the principal's response even though she hasn't pressed the 'listen' button yet.
Precious is supposed to be living in Harlem, yet when she takes the '1' train to the alternative school, the train station clearly says "Dyckman" which is in Washington Heights, not Harlem. In addition, she gets off at the "167th St." station on her way to the alternative school. The school is on 125th St. in Harlem in Manhattan, the 167th St. station is in the Bronx.