When Coffy is taken to the river under the freeway, the weather goes from dry, to raining, to dry again.
When King George is placing drugs into a fake film cartridge, his shoulder holster in on the right; in the next scene, when he's placing his stash away, the holster magically switches to his left. In the same scenes, Meg's bandages switch hands.
Actor in mirror has sleeves rolled down at 06:24 and sleeves rolled up at 06:30 while in all other cutaways his sleeves are up.
It is hot & sunny when King George is taken in his own car, then can see that is raining when the car first stops (see back window) and the weather is back to being hot & sunny during the noose sequence.
When Mac is trying to run down Coffy in his police car, the high-beam headlights are on and off between several shots.
The decal on one of the cop cars has been put on sloppily. The word "police" is noticeably wrinkled.
Obvious dummy when Coffy runs down a thug while crashing through Vitroni's house.
When the cop car turns over near the end of the film, the numbers 493 can be seen on the car roof in a dark outline where obviously numbers had been removed.
When Harriet comes back and catches Priscilla talking to Coffy, she throws a chair at Coffy and it misses and hits the wall. After the impact, Harriet audibly says to Coffy, "Come on, bitch!" But if you look at her mouth during the impact a moment earlier, she clearly said the same line just then as well, and it was dubbed out by the foley used for the sound of the chair breaking.
During the scene in which George is adding drugs to the fake camera canisters, a crew member (and shadow) can be seen briefly in left frame.
Brunswick mistakenly calls the character of Ramos by the actor's real name: Ruben.
Vitroni's henchman Omar called Coffy's gun "professional equipment". A suppressor (aka "silencer") on a revolver is anything but professional - it's useless. This, however, is a common mistake in many films.