When Spooner and Calvin are looking for Sonny at the warehouse, Calvin checks the computer, which says that there are 1001 robots present in the room. This is incorrect. There are 31 lines of robots from front to back. From left to right, there are more than 37 columns. Only 37 columns can be positively counted, but there are definitely more, as they can be seen as the camera pans. This means there are at least 1147 robots in the room, not 1001.
When Dr. Calvin first goes into her lab to question Sonny, she has to go down several steps. As the camera angle switches from back to front, she takes four steps down. However, there are clearly only three steps.
When Spooner is holding the cat after escaping Dr. Lanning's house it shows his right hand rubbing the cats neck/back and than in the next shot from the rear it show his left hand patting the cats neck/back, and in the following shot from the front again it shows his right hand back in the original position.
When Detective Spooner enters his Grandmother's house the first time, he gets down on the floor and crawls in an attempt to go unnoticed. As the shot switches to his Grandmother and back again he is in a different position on the floor, closer to the wall on the left.
When Farber runs across the street to catch up with Spooner, we can see a Sushi Express behind him. After the 2 speak and Farber turns to walk away, we can see they are standing in front of Sushi Express.
When Spooner first arrives at Lanning's house, he gets out of his car and the car door is seen closing very slowly. A second later, the camera angle changes and the car is seen in the background with the door completely closed.
When Det. Spooner is interrogating Sonny, Sonny yells "I did not murder him!" and bangs his fists down on the table as a show of anger, denting the surface with imprints of his fists. Moments later during the same scene, the table is perfectly fine and smooth.
The partially-destroyed bridge would not be able to stand in the way shown. A suspension bridge requires the large cable to be hanging between two towers. There is only one tower standing, so the other end of the cable is just dangling, not connected to anything, yet it is still supporting the weight of the bridge.
During the scene in the bar, we see Spooner drinking a beer before his superior sits down to join him. At this time the bar-tending robot says, "Your Second Round,Sir"(Confirmed by Subtitles) and sets down two more beers for Spooner and the lieutenant. But when Spooner goes to pay for the beers the tally shows '2 BEERS' $46.50. This is simply a tell of the character in that he offered to pay for the lieutenant's beer, but never actually intended to.
(at around 18 mins) Spooner pushes the delivery robot aside without even seeing if the package was for him. The door he opens (to the street) has a glass window. Later in the movie, he opens a fully wooden door for Calvin. It suggests that Spooner isn't the only tenant in the building.
When Spooner is driving back into town on his motorcycle, there are several shots that show that the cars on the road have conventional tires rather than the ball type wheels that they're supposed to have. These cars have the ball wheel props added to their fenders, but the standard tires remain visible underneath.
Sonny jumps out of the window and runs off, and Spooner and Calvin appear from the building what seems to be only seconds later (or, in this future, it's normal for a gun to remain sitting on the ground in a public street for several minutes with nobody touching it, and for a steady stream of pedestrians to carefully avoid stepping in and smearing little blue stains on the ground).
Dr Lanning has been thrown through a window and the pane has a smooth hole with no fractures in the remaining glass. This is inconsistent with Spooner's demonstration when he cracks the next pane with the chair and the glass cracks all over (as expected).
The goof items below may give away important plot points.
After the criminal mastermind is unmasked in Robertson's office, Spooner, Dr. Calvin and Sonny can be seen on a much lower floor (the buildings through the windows in the background are now taller than the floor they are on). They would then need to climb back up at least 40 floors in order to reach VIKI who is now above them.
Sonny announces as they look up the tower that there are 2,880 steps, a height of almost 2,000 feet. There is no possible way that all three of them could have climbed that many steps and arrived at Robertson's office, all the way at the top in the next scene, even more so because Spooner and Dr. Calvin don't even show a hint of perspiration.
When Dr. Calvin gets the nanites, she first deactivates the security field, and then opens a pair of glass clamshell doors to reach into the chamber. When Sonny enters the room he is attacked by another NS-5 and he throws it into the glass shattering the doors, allowing him to reach in to grab the nanites.
When the robots are attacking Det. Spooner and Dr. Calvin as they are trying to shut down VIKI, a long shot of Spooner shows him shooting at robots all around him and running. For a split second, his head separates from his body, revealing that he's CGI.