Patzer

Throughout the entire show. The Flynn house sometimes has a driveway and a garage and it doesn't.

Whenever you see Mike and Carl driving their patrol car, the emergency lights on the roof are red and blue but in Chicago, they only use blue lights - The Chicago Police Department is the only police department in the state of Illinois using all blue lights for their police vehicles.

Peggy Biggs is supposed to be from Missouri, but where Missourians say "creek", the show has her character saying "crick".