When Scudder shoots Hector in the chest, a small amount of blood leaks out of the wound, and there is no blood on the blue door behind Hector. This suggests the bullet stayed inside Hector's body. Hector continues standing for several seconds, with a small amount of blood trickling. The next second, Hector drops and the front of his shirt is drenched in blood, as well as the door behind him. This suggests an explosive through-and-through shot.
When Matt is laying on top of the fence at his house the position of the newspaper on the driveway changes depending on the shot.
(at 33:00m) When Sunny, the hooker, is thrown from bridge into the river, she is initially shown lying dead in one position along the water's edge, face-down on riverbank. In the subsequent shot, she's in an alternate position and location, more blood-soaked, and face now submerged.
During the showdown a cop guns down two criminals in the van, but the windshield piercing explosives malfunction and fail to detonate anywhere near in sync with the shot handgun.
Scudder refers to the "emerald necklace," while the actual stones in the necklace are sapphires, not emeralds.
When Angel hands over cheek slaps and hugs to his colleagues before the showdown, a boom mic operator changing his position can be seen reflecting from the side of the car in front.
Boom mic reflected in car window (at around 1h 12 mins).
Speaking at the beach AA meeting in the closing scene, Bridges' character gives his full name. In AA only first names and sometimes last initials are used.