Continuity mistake: Opening sequence, they are called to Kinzie and Dearborn. They instead show up at Franklin and Erie. After a short run down an alley, they call in their location as 3233 S. Princeton (more than three miles south of where they were, and nowhere near the Loop). (00:01:34 - 00:02:50)
Continuity mistake: During the street scenes it appears to be fall with leaves on the ground, grass green and streets and sidewalks dry. However, when police raid the park worker's house there is snow on the house roof and on the ground. When the police stake out the same house, there is no snow on the house roof or ground. (00:36:00 - 00:41:00)
Character mistake: When Ruzek and Voight are questioning Wade Henslow (the father of missing girl) at the station, after finding out he lied and set up his own security to find his daughter Adam looks at Wade Henson but addresses him as "Mr. Larson" which is actually the last name of one of the kidnappers they found DOA who got into the gun fight with his security guy, the ex-cop Kenny. (00:21:26)
Continuity mistake: Ruzek and Hailey are waiting to swap cash for guns. The pickup truck drives up very close to them and stops but then when the driver exits the truck he is parked a considerable distance away.
Continuity mistake: Dawson and Atwater are tracking a suspect at a bus station locker. The suspect takes the bag from the locker and they take off after him. They pass the same bank of lockers twice.
Character mistake: Before Kevin Atwater and Doyle fight they both put their badges and guns down on a barrel. After Atwater beats up Doyle, he retrieves Doyle's gun and holds it to Doyle's head and drops it to the ground. Atwater walks away, but he never retrieved his own badge and gun before walking away. The gun and badge are on the barrel, and he does not return to retrieve them. (00:58:37 - 00:59:32)
Chin Check - S1-E3
Factual error: The cops raid a house and find some rifle ammunition. The female cop says "cop killers." A few seconds later three cops are looking at the bullet and a box used to store it, it appears to be a 5.56x45mm round used in the AR-15 style rifles. All high powered rifle ammunition, doesn't matter if its bullet is fmj or armor piercing will go through soft armor which is what all police officers wear. Such ammo is available to civilians in every store. All rifle ammo could be considered "cop killer." (00:03:50 - 00:04:56)
Pink Cloud - S10-E5
Continuity mistake: Upton finds the young girl in the warehouse and while she is comforting her, the perp sneaks up behind her and knocks her out with a blow to the back of her head. The injury, however, from that point on, is on her forehead.
Continuity mistake: Toward the end of the episode Burgess begins to board the bus looking for the murderer. As she boards she is greeted by the bus driver who is sitting behind the wheel but as she begins to walk down the aisle the driver's seat is empty.
Continuity mistake: When Atwater finds the gun in the box, it's sitting on lined notebook paper but when Voight looks in the box, the gun is now sitting on cardboard.
Visible crew/equipment: When Antonio is talking to his CI, you can see the green and red place marking tape on the ground.
The Thing About Heroes - S5-E2
Continuity mistake: The bulletproof vest and pants Officer Ruzek is wearing change colors from dark blue to maroon and back to dark blue. The same for the bulletproof vest worn by Officer Atwater. (00:21:46)
The Thing About Heroes - S5-E2
Other mistake: Officer Burgess kicks in a door with a lock and deadbolt and does no damage to the door frame. (00:46:21)
Center Mass - S7-E14
Continuity mistake: While Rojas and Upton are questioning their suspect in the interrogation room, the plate with a sandwich is constantly shifting position from near the detectives to immediately in front of the suspect with no-one touching it.
Center Mass - S7-E14
Continuity mistake: Atwater and Rojas begin to chase a suspect out of the library where he had been spotted by a uniformed officer. As the chase begins Atwater moves ahead of Rojas with the officer in a distant third place. As they emerge from the rear door Rojas exits first, followed by the officer with Atwater behind him by several seconds.
Other mistake: Kim and Al chase the suspect into a wooded area. As Al is walking through the woods there is a puff of smoke from behind the the trees in front of him, but the suspect steps out from behind him.
Other mistake: When Voight finishes talking with Rev, Voight walks away. When he does, he goes in the opposite direction from where his car is parked and on the wrong side of car for a driver. (00:27:05)
Continuity mistake: Officer Jay Halstead shoots a suspect and jumps in to render first-aid. As he goes to render aid he tosses his police handheld radio. Shortly after, his partner calls him on the radio - he answers the call immediately and the radio is in his hand. He doesn't appear to reach for it and if he was rendering aid to gunshot victim he would need both hands. (00:19:00)
Continuity mistake: Toward the end of the show Voight and Ruzek are in their car chasing the suspect who is running. Sgt. Voight gets out of the vehicle first and is chasing the suspect toward the stairs only a few yards away. When they get to the stairs Ruzek is in the lead.
Continuity mistake: When Voight is making his "I lie for you speech" he starts talking with his office in the background but the next shot has him standing by the stairs on The Other Side of the floor.
Answer: Because he is a great cop and gets the job done better than anyone.