As Capote and Harper Lee converse with Alvin and his wife at the table near their kitchen, Capote's cigarette is almost finished. In the close-up of Capote, the cigarette is longer.
When the girl is knocking on the Clutters' front door we can see two large windows on either side of the door. In the inside shot, these windows do not exist, suggesting the inside was filmed in a different house.
In the early scene of Capote riding in the passenger seat of the Chevy, a passenger-side mirror is seen. All exterior shots of the car show no passenger-side mirror.
In the kitchen scene, when shot from Truman's back the martini glasses are empty, when shot from the hostess perspective the martini glasses are full. Truman fills the martini glasses at the end of the scene.
The car they use to drive around town keeps changing from a turquoise Chevy to an earlier model yellow and white Chevy. Sun shades on the windows are visible from inside the turquoise car, while the yellow car has none.
Although depicted in several scenes typing furiously on a typewriter, Truman Capote was famous for writing everything in longhand. He never typed any of his novels or short stories.
Truman Capote never viewed the murdered members of the Clutter family at the funeral home, as he didn't arrive in Holcomb until several days after their funeral had taken place. According to "In Cold Blood", the detail about the heads of the deceased being wrapped in gauze was related to Capote by Nancy Clutter's friend, Susan Kidwell, who visited the funeral parlor with Nancy's boyfriend Bobby Rupp, while the caskets remained open.
In the movie, Capote's hair is parted on the right side. All photos of Truman Capote show him with his hair parted on the left.
According to William Shawn's sons, he did not arrange for Richard Avedon to take pictures of Smith and Hickock, did not arrange Truman Capote's reading, and actually felt squeamish about the project. He also did not accompany Capote to Kansas for the executions.
Truman Capote always wore his watch on his right wrist, but in the movie it appears on his left wrist.
A character in the movie pronounces it the "Arkansaw" River. According to a state law passed in 1881, this is the correct pronunciation, yet many people also pronounce it "Ar-kan-sas".
Flopped shot: Upon entering the chapel of the funeral home in Holcomb, Kansas, Capote sees four closed caskets. Funeral custom and casket design dictate that the body be arranged so that when a casket is opened, the head of the deceased is always on the viewers left, and the foot-end of the casket is on the viewers right. In this scene, Capote approaches what customarily would be the foot-end of one of the closed caskets. Then he opens the lid and looks inside where we see the head and shoulders of the deceased.
In the arraignment scene for Hickock and Perry, the flag in the courtroom has 50 stars. In January 1960, the United States flag still had 49 stars. The 50th star for Hawaii was not added officially until July 4, 1960.
Capote complains that he has been on the In Cold Blood case for four years. In the next scene he is invited to a party celebrating the movie To Kill a Mockingbird (1962). But four years after the murders would have been late 1963, and four years after he met the murderers in January 1960 would have been at least 1964.
When Capote purchases baby food to nurse Perry Smith back to health, several of the soup can labels on another shelf have UPC bar codes and ring-pull tops.
Capote's hotel room has a plastic bottle of soda.
Jack carries a bag of groceries into the kitchen of the Spanish villa. The bag is a plastic, two-handle, "T-Shirt" style bag that was not introduced until the late 1970s.
In the opening wide shot of the wheat fields, we can hear strong wind gusts, but the field is still.
When Harper Lee is leaving Spain, she briefly chats with Capote then gets into a cab to leave. We hear the engine start, however both of the Cabbie's hands are on the steering wheel.
When Harper Lee is leaving Spain, Capote walks her out to the waiting taxi. When they both bend over to put her suitcase into the trunk, a cordless microphone unit can be seen just under Lee's shirt, attached to the waist of her pants.
As Truman and Harper drive to Danny Burke's residence you can see the reflection of the (modern day) towing car in Truman's side mirror.
Harper Lee is picked up in Costa Brava, Spain, by a taxi with French license plates.