Factual error: In the shot where the laser sights of the assailants come in through the windows and holes in the wall, their angles are far too different from each other. The shooters are standing at a rather great distance from the structure and at more or less the same height. All the laser sights should have more or less the same direction and certainly not make a sweeping motion inside the room.
Factual error: Throughout the movie the patches on the Detroit Police officers uniform is incorrect. As is the Sheriff's uniforms from the prison bus. The Sheriff's department patch has a picture of the state of Michigan in the center, not a star. I do not believe that Detroit police officers even have patches on their uniforms.
Factual error: The movie is set in an about-to-be-abandoned precinct station house in an old "bombed-out" industrial section of Detroit. Much is made of this locale throughout the film & exterior shots show surrounding empty factories, warehouses, etc. In the next to last scene, Laurence Fishburne, Ethan Hawke, & Gabriel Byrne have the final shoot-out in a completely wild, 30 year-old growth, lodge-pole pine forest, having walked there in a few minutes from the precinct. In the last scene, rescue workers come "out" of the forest on a rutted dirt road with a very fake-ily pasted on backdrop of the Detroit skyline in the distance.
Factual error: In the laser sight scene where lasers are coming into the building from all angles, you see the entire sight line of the laser. This is impossible in real life: you will only see the point where the laser hits a solid object - there must be something substantial to reflect off of besides air. There would have to be an incredibly dense fog inside the building to see the entire laser light, and even then it would be intermittent with the changing density of the fog layer.