Samaritan

When Danny talks to Frank after dinner, it is explained how he was demoted from Major Case Squad to a precinct detective due to his handling of the Capos case in the pilot. This also explains why he has a new partner.

If you listen closely you will find that Danny was moved to Major Case. He was concerned that it looked like favoritism. Frank explained that the Chief of Detectives made the call.

Danny Reagan catches a ride with his brother and his sergeant in a patrol car. When they find the open subway hatch he gets out off the back seat on his own. Patrol car back seat doors don't open from the inside for obvious reasons.