Larry tells Herrmann that their father was in Boston selling merchandise to Filene's Basement. That store chain went out of business in real life on December 29, 2011, though it could have continued on in the universe in which the show takes place.
In the first scene, when the crew of Truck 81 is running toward the apartment building with the boy stuck in the trash chute, they run past their station. The sign on the firehouse reads ENGINE COMPANY NO 18, which is the real Engine housed at this fire station when the show is not filming. (Engine 51 is not a real or current engine, just used for production).