Characters are frequently seen drinking socially and smoking tobacco. A character is seen drinking alcohol from shot glasses and has slurred dialog indicating that he is drunk. Strong tobacco is used by a character as a stimulant to keep awake and alert for a long vigil ahead A character is seen drinking more and more, presumably to calm his nerves.
No illicit drug use is seen or referenced to though there is frequent use of alcohol and tobacco including a couple scenes of alcohol abuse.