Revealing mistake: During the hovercraft battle scene, the guy behind Bond is supposedly out cold, but when Zao is shooting at Bond's hovercraft and the shots are hitting the fan shroud making Bond wince, the unconscious man can be seen covering his ears from the explosions. (00:09:30)
Revealing mistake: In the scene on Isla Los Organos, when Jinx is with the doctor at the clinic, she shoots him twice. But when you see her shoot him the second time, her gun produces no muzzle blast or smoke, and no spent bullet casing is ejected. (00:43:25)
Revealing mistake: During the sword fight in the castle a sword penetrates a glass panel behind which stands an armour. The armour is then pushed through the glass panel behind it. The first glass panel breaks in big pieces (probably the usual 'sugar' glass), whereas the second glass panel shatters properly. (00:55:35)
Revealing mistake: When Q shows to James how the ring works, the bullet proof glass breaks into pieces but you can still see a reflection. They arguably put two windows in front of the camera, one that Q breaks and another one to protect the camera lens. (01:02:50)
Revealing mistake: When Bond is in the car following the goons heading into the facility, it shows the techie guy scan a card and then swipe it to open a door. Before he swipes it, the door is already opening. (01:13:15)
Revealing mistake: During the James Bond windsurfing scene as he was escaping the ice, his hair and suit are dry in what seems to be 50 foot waves. (01:30:30)
Revealing mistake: When the bad guy fires at Bond with the mini-gun attached to his green Jaguar, you can see that the gun does not have an ammo feed. (01:33:40)
Revealing mistake: After the helicopter escape at the end, a red sports car is sticking nose-down in the ground after falling hundreds of feet down out of the aeroplane, without a single crack in the windscreen, in mint condition. The yellow one only has the right door open. (01:59:30)
Revealing mistake: When Jinx shoots the scientist through the check, there is a slight mark on the check exactly where the bullet will go.
Revealing mistake: During the battle scene between Kill and Bond, some of the lasers pass through Kill, and nothing happens to him.
Revealing mistake: As Bond's car is hanging on to the ice by its parachute you can see it's not Pierce Brosnan but a stunt double.
Revealing mistake: In the scene inside the melting palace Bond smashes the wind screen and saves Jinx. While he's driving around water is pouring down, however no water comes into the car and Bond's face is totally dry.
Revealing mistake: In Korea, James takes a hovercraft to escape from the base. He throws one soldier outside and knocks out another one. When the son of General Moon collides with him, you can see that the knocked out soldier is obviously a dummy.
Revealing mistake: As the invisible car creeps through the snow in reverse, the rear tires make tracks in the snow, as one would expect them to. Then the front tires go by, and the tracks do not change. It is impossible for the front tires to not have made tracks of their own, which should be visible, even within the existing tracks.
Revealing mistake: One for swimmers to look for; when Bond is swimming beneath the ice near the ice palace you can see that he has a screw kick, but in the shots where you can see Pierce Brosnan's face you can see that behind him his legs are kicking correctly.
Revealing mistake: When Bond climbs onto the bigger hovercraft, the smaller one overturns and you can see it's an obvious dummy sitting in the back.
Answer: By this stage, it's become a habit.
J I Cohen