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.
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)