Visible crew/equipment: While People's brother is waiting in the car he gets shot in the head. If you slow the scene you can see an empty blood sack near the back of the window.
Factual error: In the scene where Shaft has chased the guy running from the drug bust and caught him in the hall with an empty gun you can plainly see the slide is locked back on the bad guy's pistol (indicating an empty magazine). When Shaft steps out to arrest him (before the bad guy jumps out of the window into the other building) you can clearly hear the 2 clicks of a firearm hammer falling on an empty chamber. With the slide locked back, the hammer is locked back also...it would never make any clicks.
Continuity mistake: When that Latin drug dealer got hit by the car with the two brothers of the waitress inside, you can see that the glass gets broken. But in the next shot, where the brothers step out of the car, the glass is whole.
Continuity mistake: When Shaft and Peoples have the final duel at the end of the movie, you'll notice Shaft has a holster across his right arm and there is a gun in it. When he grabs for the gun, he reaches into the holster, but when they get the close up of him pulling the gun out, you can clearly see he is reaching under his shirt, and the holster's disappeared.
Continuity mistake: Watch Shaft's goatee. The strip of hair running vertically under his lip constantly changes in thickness throughout the movie. At one point it will be wide and in the next scene it will be noticeably thinner only to change back to wide in the following scene.
Visible crew/equipment: During a car chase with People's gang, Shaft blasts away at the baddies causing their car to crash and somersault over other parked cars. Just along from this carnage, there is a huge studio spotlight just in an ally along with other lighting equipment illuminating the scene.
Audio problem: While rescuing the witness from her safe house near the end of the film, Shaft and the witness run across the street to Shaft's waiting car. They comes under a barrage of gun fire from the driver of People's car. The shot shows his gun breech is empty and the actor is just pulling the trigger while the effects sound like he is firing.