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 - 00:41:00Snag.1
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.
Character mistake: When Detective Olinsky calls out a license plate to Detective Upton he uses the wrong police phonetic alphabet. He uses the word Andy for A instead of the standard word Alpha.