Arnold Schwarzenegger spent three months learning to speak Russian. Jim Belushi spent two weeks working at a Chicago police district headquarters.
Walter Hill, thinking Arnold Schwarzenegger was too muscular, asked him to lose ten pounds for his role, and Jim Belushi to gain ten pounds.
The film is dedicated to its stunt coordinator, Bennie E. Dobbins. Dobbins died of a heart attack on the set while staging the film's snow fight scene in Ramsau, Austria.
In an attempt to best convey to Arnold Schwarzenegger how he should capture the essence of his character, Walter Hill suggested that he watch Greta Garbo's performance in Ninotchka (1939) and emulate her character. Schwarzenegger complied and, according to Hill, got a handle on his character right away.
Vagran Rosatavili, Viktor's brother, is played by one of Hungary's leading action-movie actors, Gábor Koncz. In an interview, he said that until he met Arnold Schwarzenegger he thought of himself as a muscular and tough actor. He subsequently described himself as a "small potato".