When Lance asks Undercover brother about the show Friends, he asks what Ross saw of Julie's in the third season. This happened in the second season, Julie was not on Friends in the third season. He also calls her Julia instead of Julie.
As the B.R.O.T.H.E.R.H.O.O.D. team infiltrates the Man's compound in the "Island Fortress Cleaning Service" van, Dave Chappelle's tongue is green. Evidently he had been sucking on a piece of candy just before the scene was shot.
The helmet of White She Devil changes during the motorcycle chase: in close-ups it is a more open model so you can see her face, in wide shots the helmet covers her face (presumably to obscure the use of a stunt double).
When UB is cutting the outside glass to the mainframe room, he draws a rather wavy circle with the glass cutter. When he taps on it and the glass around the circle shatters instead, he's left with a perfect 360 degree glass circle (including sanded edges).
Towards the end of the 'Caucasavision' part, when Smart Brotha is looking at UB, you can see one canister behind him. But when Lance walks with Smart brother across the room, there are suddenly three canisters.
When UB and Sistah Girl are outside of the brown locked door at the golf course and are surrounded, UB's shoes extend and they walk onto the roof. But immediately after wards, he looks at her and says, "Thanks for the lift." They are back on the ground in front of the door.
The "Catfight" between Sista Gurl and White She-Devil. When White She-Devil hits the shower knob to turn it on, she turns the knob down. But throughout the shower scene, it stays in the middle, neither up or down.
When UB's license plate slides away to reveal the nozzles, Toronto's distinctive CN Tower is clearly visible in the background. Undercover Brother's city is never named, but it is supposed to be American.
She-devil's henchmen's motorcycles are both stock 2002 Honda CBR600's but when one of the bikes crash to the wall and explodes it is a circa 1997 Kawasaki ZX-6R with clearly visible stunt equipment (special tires, handlebar) fitted and the rear fairing painted to look like a Honda CBR.
When she-devil and her henchmen take off to the chase and are starting their motorcycles, the instrument cluster shown (a circa 1995 Honda CBR600) doesn't match she-devil's (1997 Kawasaki ZX-6R) or her henchmen's (2002 Honda CBR600) bikes.