In the initial shoot-out, a bad-guy is shot and falls off a make-shift bridge. He very clearly lands on his back. In the next shot, we see him lying dead, face-down.
At the end of the movie when he approaches the tied up woman with the hammer the pointed end is facing forward. After being shot a second time and lying dead on the ground the flat end is facing forward.
When Eddie Cusack (Chuck Norris) saves Diana Kuga from Comacho's thugs in the alley, and Angel escapes with her anyhow, Eddie fights he remaining four thugs starting out with a gun in his right hand, and hits the first three with the gun, but as he hits the last thug with his right hand and runs after Diana, the gun is missing.
When Diana Luna is chased by Comacho's goons into an alley and cornered near a dumpster, a red delivery truck with "CSX Delivery" painted on the back door can be seen in the background in one shot, is gone in the next shot, and returns in the following shot.
When Tony Luna and his thugs killed Victor's thugs in the beginning of movie, in one shot there was bottle of beer standing alone in corner of table. When Tony and his thugs entered the room and started grabbing money and drugs we could see same bottle but with paper money under it.
When the Prowler is being shown to the police, the claim is made that it has twin fifty millimeter machine guns. There is no such thing as a fifty millimeter machine gun. There is a fifty caliber machine gun and that has been in service in many militaries since before World War 2.
As the L train is passing over the river, Angel takes his chance and jumps. Cusack stops for a moment, says "Shit!" puts his gun in his holster and after a couple of seconds, jumps after him, hitting the water in the middle of the river, just like Angel. However, the L train is moving fast in this scene. In those couple of seconds, the train would have passed the river.
In the underground chase when the first car jumps, the spark explosive in the car chassis is detonated in mid air, well before the car lands.
The rear-view mirror has been removed from the Checker cab that Diana takes.
In bar fight, when Victor hits Eddie in face for first time, if you watch carefully you can see that he actually misses him.
The police car that Eddie commandeers has neither a rear-view mirror nor a partition between the front and rear seats.
Near the end of the movie, the bruise on the girl's mouth switches from the right side back to the left side.
When Giamani is following Diana out of the museum, a man in a brown suit is staring directly at the camera.
When Dorato is searching the bar for Cusack he walks past a Frenzy video game machine, the only video game in the bar (next to a Playboy pinball). But the sound of the Moon Cresta video game is heard instead.
As Cusack approaches the bad guys' pool hall and is exiting his car, a small crowd and a uniformed police officer are clearly visible across the street near the sidewalk.
When the drug deal is transpiring, Spider is translating between Victor Comacho and the man he is selling the drugs to and before they get killed, Spider says, "You can always depend on Spider," in English, after having to translate between English and Spanish throughout the entire scene.