During the gunfight in front of Diane's house, one of Peoples' thugs is seen firing a nickel-plated Beretta pistol at Shaft. The thug pulls the trigger numerous times, but the slide clearly locks back after the first shot, indicating that the gun is empty.
In the beginning, the victim has been bludgeoned in the back of the neck. However, in the flashback, Walter hits him almost dead on in the face. Even within the flashback there is an error; from one angle the victim is quarter turned to face Walter, the next shot he is completely turned around.
When Peoples' brother is shot in the head, blood sprays on the back window. But after Peoples is run over and gets back into the car, his brother is still there yet there is no blood whatsoever on the window.
In the scene where Jimmy and Jack ambush Shaft, there is a shot where Carmen raises her gun and aims it at Jimmy's head. His left shoulder is clearly visible as he stands infront of her. Carmen shoots him in the head and his shoulder is still visible as she lowers her gun. In he very next shot he is slumped against the wall dead.
In the final chase with Peoples as the two cars race by the warehouse you can see a large 10k light on a rolling stand, a smaller light resting on the curb and a crew member sitting next to the rolling stand. This group is visible on the side street the two cars drive by.
When Walter Wade Jr. gets into yellow cab to go pawn the jewelry, he tells the cab driver to take him to 47th and 5th. The following shot shows Wade Jr. coming out of a jewelry store with the cash and walking away. As he walks away the green street sign on the corner clearly says 79th St. 47th and 5th is nowhere near 79th street.
In the flashback, Diane Palmieri has blood on both sides of her face, with Wade's fingers on her left cheek and his thumb on her right jaw. Presumably, she cleaned her cheek but not her jaw, leaving the spot seen at the beginning of the movie.