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.
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.
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.
Answer: It's been used several times. Nolan's first T.O., Bishop, used it during a home invasion call for one example.