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.
Character mistake: Alvin Olinsky appears in this episode investigating the bombings in which Trudy was involved, but he died at the end of season 5.
Suggested correction: Where do you see Alvin (or even the actor Elias Koteas) in the scene? I couldn't see him in this episode.
The Song of Gregory Williams Yates - S3-E13
Other mistake: Lindsay is video calling on Nellie's mom's phone to Yates. Bought at the scene of a fire, tells Finn to text Lindsay and let her know about the fire. We see the text come in, but it's on Nellie's mom's phone, not Erin's. (00:31:00)
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)
A Night Owl - S3-E14
Continuity mistake: When the woman came into the precinct and showed Erin and Voight her daughter was taken on her phone, she dropped her hand after Erin took it. The very next shot from the reverse still shows her holding the phone as does Erin.
Factual error: Kevin sleeps overnight at woman's apartment. He doesn't share that he's a cop. The next morning in his unmarked police vehicle he uses his handheld radio that was appeared to be stored in the console and shows up on a violent scene with his weapon. It's obvious that Kevin used his official vehicle for personal reasons, and stored his radio and weapon in the vehicle unprotected overnight, which every police officer knows is wrong and a violation. (00:03:53 - 00:04:29)
Factual error: 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 "Adam", as is used by Chicago police. (00:35:00)