Continuity: Changes in the time on the clock in the living room when the cop is listening to the CD that's been dropped off for him.
Crew or equipment visible: Wires can clearly be seen on the windshield when SP Wong lands on the taxi.
Continuity: The birth date for "Chan Wing Yan" in his electronic career file is 23 November 1970, but on his headstone it is 25 October 1966.
Audio/visual unsynchronized: During the funeral scene at the end, the drummer is not synchronized to the sound.
Continuity: When SP Wong was killed, the top of the taxi had been collapsed, but in the next scene, the top of the taxi remained undamaged.
Continuity: In the scene where SP Wong falls onto a taxi cab, the blood stain on his mouth changes between shots.
Revealing mistakes: When Yan arrests Ming on the rooftop, it is clear that his Glock contains no magazine.
Continuity: When Lau goes to listen to the "sampler" CD that's been dropped off for him, he presses the button on the player and we see the CD drawer close twice - first in the long-shot, and then in a close-up that starts from a fully-open position on the drawer.