In the car chase at the end, the passenger window of the yellow car is shot out. In a shot later from a different angle, the window is intact.
After crashing the police motorcycle, Chev throws away his cell phone. However, he has his phone again in subsequent scenes, such as the helicopter scene at the end.
When Chev is running through the hospital corridor, he tucks his handgun under his left armpit. In the next shot, when he jumps off the wall to get around some people in his way, there is no gun in sight on him. Since he is wearing only a loose hospital gown, it would be impossible for the gun to be secured anywhere but in his hands or armpits. In the next shot, he has the gun in his right hand.
When Chev Chelios is projected into the elevator he fires a shot at the police and the slide doesn't return, indicating the magazine is empty. When the shot cuts to another angle of Chev, the gun the slide is returned forward.
Throughout the car chase, the yellow Volkswagen convertible (which somehow can outrun two larger far more powerful cars) is shot at close range, multiple times, by thugs with automatic weapons. While the glass is shattered, and reappears several times, the body itself never shows any signs of having been hit by a bullet.
When Chev jumps into the pool with Carlito, he still has his cell phone in his pocket. He later uses it, and it is working perfectly; the model of cell phone he uses is not water-proof.
When Chev's doctor calls to check on the effects of the adrenaline, the camera shows an aircraft that the doctor is supposedly on board. The aircraft they show is actually a Singapore Airlines Mega Ark which is a cargo aircraft and has no commercial passengers. You can tell this is a mega ark by the distinctive insignia on the bottom of the nosecone.
In the hospital, Chev attempts to "energize" himself using a defibrillator. The goal of defibrillation is to stop the heart, not start it, speed it up or increase adrenaline. Best-case scenario, Chev would have stopped his heart and it would have reset itself but it's more likely he would have just died.
Jumping into a pool instigates the mammalian diving reflex, which allows the heart rate in humans but 15-25% on submerged contact with water. If the lead character is experiencing adverse reactions to a resting heart rate, jumping in a pool would cause him to crash.
In the end Chevy falls from a helicopter on a car and smash it and jumps like he has fallen on the car made of rubber. He would just make a deep dent in the car and stay in it, not jump and fall on the pavement.
The three middle fingers of Verona's hand are shot off in the final sequence, but when they're falling from the helicopter if you freeze-frame it the fingers have returned.
(at around 17 mins) While Chev Chelios is in the back of the first taxi listening to "Achy Breaky Heart", the wide shot shows vehicles driving on the wrong sides of the road. This shot is reversed, with drivers on the right side of their cars, and with the taxi's lettering backwards. The taxi was really going right-to-left.
In the scene when he is running down the street, after he leaves the hospital, he passes two cars parked on the left: a Del Sol and a Mustang). Their images are reversed making each car appear RHD, and their license plates backwards.
When Chev is at Doc Miles' office, he gets the epinephrine via an intravenous infusion. In this scene, the regulation clamp is closed.
When Verona pulls a revolver on Chev on the rooftop toward the end of the film, you hear the hammer being cocked, but you can see it is in the uncocked position.
When Chelios is standing on the police motorcycle, in the background there are police directing traffic and a crew member on the far left.
When Chev is sneaking up beside the car to steal the police bike, the camera operator is seen reflected on the car.
When Chelios is driving the police motorbike on the bridge/freeway, you can clearly see the red light of the camera shining from his shirt and soon from the wheel of the bike.
When an external shot of the taxi cab is taken during the "Achy Breaky Heart" scene, you can see the shadow of the camera person on the street.
Throughout the movie, references to "Chinese" items and characters are continually made. "Don Kim" is said to be Chinese though Kim is traditionally a Korean name. In the "Chinatown" section of the movie, when the school girls are interviewed for the news, they are speaking Korean. Also in the warehouse the workers also speak Korean. A hint that this is a purposeful "mistake" by the director/writer is made when, in the hospital, a page is heard calling for anyone who can speak Korean.
When Doc Miles is consulting Chev on epinephrine while Chev is driving a taxi, he says that epinephrine comes in 10mg syringes. The syringe that is shown later and that is actually used to store epinephrine in places like ER contains 1ml of epinephrine. 1mg/10ml epinephrine solution is usually used, so Doc is clearly wrong.
When Chev is administering the shot of epinephrine at the hospital, he goes to the trouble of finding a vein. Epinephrine has an immediate effect, he could have injected it anywhere.