Originally, Ray Liotta wanted the role of Sheriff Freddy Heflin, while Sylvester Stallone wanted the role of Gary "Figgsy" Figgis.
There is a disclaimer at the end of the credits which states "This film is a work of fiction. It is currently illegal for New York City Police officers to live outside the state of New York."
Sylvester Stallone gained the necessary weight for the role by eating a steady diet of giant pancakes served at a local pancake house.
The sandwich scene in Robert De Niro's office was Stallone's first day shooting. The sandwiches, which were an afterthought for the actors' lunch, were improvised into the scene by De Niro.
Robert Patrick got the part after running into Peter Berg and producer and music supervisor Meryl Poster, who were staying in the same hotel in New York City. He got the script, and then read for writer and director James Mangold a few days later.