Capp and Hadley have a prank worked out to play on Candidate Pete Mills - they race into the lounge yelling for Mills and frantically ask him if he parked his car ACROSS THE STREET, Mills sees the panic on their faces and says "Yeah, why?". They say "Come with us - QUICK!!" Seriously alarmed, Mills rushes outside with the 2 guys - but the next 4 minutes are ruined by the fact that his car is parked on the SAME SIDE of the street as the Fire Hall.
The CFD is shown as having spent a lot of money on sexual sensitivity training, yet they still use intergender locker rooms and bathrooms.
Det. Voight sees the criminal charges against him dropped, so he is released from jail. Since police officers are held to a higher administrative standard which requires a lower burden of proof for action, he would not have a basis for a wrongful termination suit as a character suggested. He also would not be reinstated to police duty as shown, much less promoted. An example of this are the LAPD officers that were acquitted of beating Rodney King but were terminated from the department for misconduct.
Unless administrative rules allowed filling the commander position with anyone, a trainee would not be promoted up several ranks as was shown.
Tara suggests Severide make an Alford plea regarding her complaint against him, saying it is an "apology on the record". First, an Alford plea is made in a court of law, not before an administrative board. Second, the plea is not an apology on the record. It's a plea of guilty in which the defendant asserts his innocence but acknowledges that enough evidence exists to make a guilty verdict likely.
At the car crash, no one thinks to reach in the driver window and turn off the ignition. A firefighter eventually breaks the rear window and does so, but this would have been done much sooner.