When Basquiat is painting the Amoco sign, the white stripe runs completely through the black horse. But when Andy Warhol approaches the sign, the white stripe does not continue through the horse.
When Jean Michel is first painting in his new basement studio, he's painting two paintings simultaneously; a large and a small one, both on the floor. He paints a large black stripe on the small one, which disappears then reappears between shots.
When Basquait gives Rene the "mostly brown coloured" painting he asks Rene the time and then writes down 'RENE5:11' on the painting. This addition to the painting keeps appearing and disappearing.
When Basquiat is painting on the floor in his studio, part of the painting in the upper-left hand corner disappears and reappears.
When Basquiat goes to look at the basement studio, he leaves the house in his pajamas and robe. When he arrives at the studio he is wearing a different shirt under the robe.
When Basquiat barely walks on the street after screaming at the asylum guard, when his younger self is running towards him, the child should disappear behind Basquiat, but you can clearly see his hand behind the main character for a few moments.
In the first scene where Basquiat does graffiti, there is a "Sane" tag next to him that reads "SANE 95'" when the movie is supposed to be set in the early '80s.
As Basquiat walks with Gina for the first time, a woman is seen behind them walking a dog on a retractable leash. Retractable leashes were not available in 1981.
Gina has a Diet Pepsi can from the 1990s when she goes to Basquiat's meeting with the Krugers at his studio in the 1980s.
When Jean Michel discovers that Andy Warhol has died (which occurs in the mid-'80s) there is the store X-Large in the background. X-Large, (created by Mike D from the Beastie Boys) did not open or have clothing until the early nineties.
Several cars in the background are from the '90s when the date of the activity is early-'80s.