Ronnie says to Stottlemeyer, "What are you going to do? Hit me with a phonebook?" In the old days, interrogators had ways of inflicting pain without leaving marks on a suspect. By smacking a heavy phonebook straight down on the top of someone's head, they can compress the cartilage disks between the neck vertebrae. This is very, very painful without damaging the scalp.
The photo that Edie the ex-wife gives to Stottlemeyer and Disher is a still of the exact establishing shot of the next scene where Joe is following Natalie at the grocery store.
The interior of the 'airport' is everyone's go-to location in Los Angeles - Union Station, the downtown train station since 1939. The main lobby, concourse to the trains, and the luggage carousel were used in this show, as was the marshaling yard for the exterior. TV shows and movies are filmed there all the time, including Ray Donovan and Hail, Caesar.
Some of the locomotives In the rail yard are marked BVSE. They are, in reality, BNSF - Burlington Northern Santa Fe.