Goofs

After informer Foxy gets beaten up, shot, and and thrown into the river by Johnny Wong's thugs, he manages to make his way to the police station with dry clothes and a bloody face.

After shooting the mysterious "machine gunner" at point blank range to end the Teahouse shoot out, the shot Tequila fired leaves a gory glob of blood on his face. However, when Tequila rushes to the side of his fallen partner, Benny in the Teahouse, the blood on Tequila's face appears to be only a small dried smudge on his face even though it's supposed to be just moments after Tequila shot the thug. While Tequila could've wiped his face, there's less kitchen flour on his face and clothes than a moment ago as well.

Location and the position of Benny's (Tequila's partner) body in the Teahouse. When he was shot, he was inside the kitchen with the door entering the kitchen to his left. Yet after Tequila comes to his side after the shoot out, Benny is outside the kitchen on the floor in the dining area. That would mean that as he was being shot, his body would have to have had to make a left turn to get back out side the kitchen even though he was seen being shot and falling within the kitchen.

When Tequila decocks Alan's Beretta twice while confronting him on his boat.

When Tony and Tequila blow their way out of a weapons storage vault, they use 2 pieces of C4 and detonate them with a grenade. A grenade can not detonate a C4 charge; only a detonator can.

Foxy's life is saved by a metal lighter in his pocket. In real life, a lighter would not stop a bullet whatsoever, much less at point-blank range.

Throughout the film, characters fire more bullets than their guns would realistically allow without reloading, John Woo actually explained that he does this on purpose because reloading slows down the action scene.

Often when someone gets shot, a flash can be seen at the exit wound. Bullets do not make flashes at the exit wound, so this is a miniature explosive charge used to make the wound appear as an effect.

When Tequila empties the shell casings from his revolver after the warehouse shootout, the shell casings are blank shell casings, not real bullet shell casings.

At the end of the Wyndham Teahouse shoot out, Tequila (Chow Yun Fat), covered in flour, executes the mysterious gunman in the kitchen at point blank range with a single shot of his pistol. However, the slide of the semi-automatic pistol does not blow backwards to cycle the next round after Tequila pulls the trigger. In reality, this would indicate that the pistol would have failed to fire. It is possible that they had the actor fire an empty gun, or a non-firing prop gun, for safety purposes.

When Tequila's partner shoots the undercover cop in the tea house, the blood from his wounds clearly spurts from his vest & not his body.

(At around 1h 51m) When Teresa shoots the bad guy at point blank range after he slaps her, the bullet holes in his abdomen only appear a few milliseconds after the shots are fired.

In the first shot of Tequila sitting down in the teahouse, right beside him is a man wearing a black shirt who keeps swaying in every direction while admiring a bird in a cage and briefly looks at the camera.