When Nolan is in the squad car at the beginning of the episode, he is clearly seen wearing a short sleeve uniform shirt. When he exits the car at the hospital he is back in the long sleeved uniform shirt he was wearing in the season one finale.
As Season 1 ends, Tim faints on the front lawn under gray skies and rain. Then on the way to the hospital to start Season 2, it's a gorgeous, sunny day without a cloud in the sky.
When the officers are being shot at at the hospital, Lopez calls for backup, but instead of saying 7 Adam 7, which is the call sign for her and West, she says 7 Adam 15, which is Nolan's call sign.