Factual error: During the LAPD gun exchange program, an explosion happens from (according to the show) claymore mines being in the trunk of a car. In reality, this wouldn't happen as Claymore Mines are very stable and safe. The explosive used, C-4, is shock stable and temperature stable. The mine will only go off when used with a detonator.
Factual error: While talking with the gang leader alone, Bradford declares, "I'm never alone," and suddenly a swarm of officers descend on them, and a helicopter appears directly overhead. The helicopter makes no noise until the spotlight is turned on. A helicopter makes deafening noise and can be heard from miles away. There's no way you could be surprised by one being directly above you.
Greenlight - S1-E16
Factual error: Captain Anderson pulls a suspect underwater and shoots him. There's a bright, yellow flash under the water. In reality, this wouldn't happen, only a large amount of bubbles would appear, but no flash.
Warriors and Guardians - S2-E4
Other mistake: The driver in the blue Mustang (Osito) drives past Nolan and Harper, then makes a u-turn and drives past them again, to Nolan and Harper's left (same direction he came from), but when Nolan and Harper go to chase him, they turn right instead of left. (00:31:15)
Continuity mistake: When Angela is eating a pickle with Marshmallow fluff, there is only one more bite of pickle left. However, when the camera turns, she has a whole pickle again. (00:05:15)
Revelations - S3-E6
Continuity mistake: When Tim puts Lucy in the squad car after "arresting" her, the rear door on the driver side is open, but when the camera pans back to her it's suddenly closed without making a sound.
Revelations - S3-E6
Continuity mistake: When Nolan is asking for advice from his ethics teacher, she says, "It's 2021." However, with the 2019 start time for the rookies and a supposed year's probation, this shouldn't be possible from the show's timeline perspective.
Continuity mistake: In the episodes before "La Fiera," Nolan's new truck is a black Toyota Tundra. However, after that episode, it changes to a Nissan Titan, yet his character still says, "black Toyota Tundra."
Other mistake: In the morgue, officer Thorsen says that Harper can use his reservation at a certain restaurant that evening, and she texts James to ask him out. But Thorsen never told her the time of the reservation, and yet she manages to tell James that it is at 7 pm. (00:22:40)
Hit and Run - S4-E8
Factual error: Tim says, "At approximately 1057 hours" for the scene, but in the scene, it's shown the time is 10:14. The time should have been said, "0957 hours" for when the suspect attacked Nolan and Harper. (00:13:00 - 00:13:22)
Continuity mistake: Austin and Tamara are standing and picking out snacks at the attorney's office. Lucy walks up, and Austin and Tamara turn around. His hands are by his side. When the camera angle changes, his hands are in his pocket. (00:18:29)
Character mistake: When the sergeant's partner gets shot and Chen calls it in, she says he got away in a black Buick, but the car was a Honda Civic. (00:10:52)
Training Day - S6-E4
Continuity mistake: When Tim and Aaron are questioning a suspect, Aaron comes out of the room to talk to Tim and shuts the door behind him. When it cuts back to Aaron, the door is open. (00:09:16)
Answer: Window tool.