The behind-the-scenes footage of 21 Grams

·The film was shot almost entirely with handheld cameras.

·The film was shot in chronological order (although in the final editing process, it was not in chronological order)

·Paul and Cristina were in the restaurant, and he quoted Venezuela The poem by the Nella poet is "La Tierra Giró para Acercarnos", the author's name is Eugenio Montejo.

·There is a scene where Jack Jordan wants to hang himself, but an overweight prisoner saves him. There is a big tattoo on his chest that says "Maria Eladia". This is the film The person to whom it is dedicated, Alejandro González Iñárritu, is the name of his wife.

·Naomi Watters agreed to star in the film without reading the script in advance.

·Paul found a photo of Christina and her husband in a book. The book he is looking at is called "Cruising Paradise", written by playwright Sam Shepard, and contains 40 stories about loneliness and failure.

·The story marked on the photo in Wandering Paradise is called "The Hero is in His Kitchen". It's about a conversation on the phone between two men, one in Tucson, Arizona, and the other in Los Angeles, California. The last thing said on the last page of the story (one of the ones marked on the picture) is "Don't be crushed by the weight of a heavy heart!"

·The ending in Spanish is Dedicated to María Eladia, "pues cuando ardió la pérdida, reverdecieron sus maizales", which translates to "when the loss is burned out, their cornfields will grow green again."

Through the lens

·Display error: After Paul fires several shots into the dirt, Jack falls to the ground, holding his head, and you can briefly see an earbud in Jack's ear.

·Continuity: As Christina crosses the street, you can see that the light is green but traffic is stopped.

·Display error: When Christina tried to give Paul Reeves a blood transfusion to save him, the nurse used a blood collection device called a Vacutainer to draw her blood. This thing uses vacuum power to draw blood. Previously, the blood vessels had to be punctured with a needle, and then the transfusion tube had to be punctured with the other end of the needle, and then a vacuum was used to complete the rest of the work. In this movie, we see the transfusion tube being readied for the needle, so the transfusion wasn't really happening at the time.

·After Paul Rivers told Jack Jordan to escape, the shadow of the camera could be seen on the ground in front of him and in the trees as he left.

·Continuity: Months after the surgery, after sleeping with Christina, Paul still has wounds on his chest from the surgery.

·Factual errors: The doctor was auscultating Paul’s heart and he put the stethoscope behind him. The earplugs were supposed to be placed forward, but it was obvious that his earplugs were placed backwards. In that position, not to mention damaging his ears, it would at least prevent him from hearing his heart.