When suspect one shoots himself in the head and is shown falling to the ground, his Beretta lands at least a meter away from him. After the next cut, the gun is loosely in his hand again.
When Officer Henry Jones and Officer Nicole put Ramon in the police car during the scene of the domestic disturbance, it was a 1995 Chevy Caprice. As they pulled up to the bank robbery it was a 1996 Ford Crown Victoria.
When Emil shoots at the guy in the pick-up truck, the man runs out and leaves the door open. In the next shot when Emil stops next to the car, the door is closed.
When Emil carjacks the truck, you can see the owner flip two switches down to disable the vehicle from being started. When Emil gets into the truck, the switches are back in the "up" position.
When the bank employee is loading the money in the black bag it seems very heavy and full. Later when they're near the safe we see the bank robber easily pick up the same bag yet it is very light and looks nearly empty.
Off duty cop played by Madsen, is being bothered by a large, noisy party next door. With no cooperation from them, he heads over with bolt cutters, and cuts through the electrical conduit supplying the house. Without electricity, the house and party go quiet. In reality, this would be incredibly dangerous, not just from electrocution, but from arc flash. In addition, the jaws of bolt cutters cannot open anywhere near wide enough to cut conduit, especially of that size.
The SWAT officers involved in the actual shootout did not make an entry into the bank until after the main two subjects were in custody/deceased.
When the police are acquiring AR-15s from the gun store, and transporting them in the shopping cart it's easy to see the bayonet lugs. The real North Hollywood Shootout took place in 1997, three years into the 1994 Assault Weapons Ban, which, among other things, banned the sale of new firearms with attached bayonet lugs and other cosmetic features. There's no way these guns would have bayonet lugs like they do in the movie.
The Training Officer, while referring to his Vietnam War experience, talks about "Chinese-made AK-47 machine gun". The Chinese version of the AK47/AKM is designated Type 56 and is considered an assault rifle, not a machine gun. A Vietnam-War veteran will surely be aware of this difference.
When Mario Van Peebles is seated in the back of the police cruiser showing the handcuffed suspect "pictures", from his picture collection he exits himself by using the inside door handle. This is totally impossible as no police cars have working door handles in the back, so suspects can't get out.
When the dead Larry Phillips Jr. is turned over, you can visibly see his eyes go from closed to open.
Several shots show the modern Bank of America flag logo which was not in use in 1997.
In a shot of some cars passing you can see a 2002 Chevrolet Trailblazer driving past, but the movie is supposed to take place in 1997.
Some stock footage of I-278 in New York City is shown for what is supposed to be an LA freeway.
When the 911 dispatcher makes a call to police units about the impending robbery, she says the robbers have "body armor and AK-47s.". However when officers Baker and Martinez call in the robbery, they say in their radio call that the robbers have AK-47s. They did not mention that the robbers were wearing body armor.
Emil had long hair and Phillips short in fact. The other way around.