Rudy "Cheyenne" Cadena was not killed by his own gang as shown in the movie. In reality, he was killed by the Nuestra Familia, the rivals of the Mexican Mafia. As a result of this murder, the Mexican Mafia formed an alliance with the Aryan Brotherhood in 1972, and the Nuestra Familia formed an alliance with the Black Guerilla Family.
According to 60 Minutes (1968), three people who acted as consultants on this film were later murdered because of the depiction of a homosexual rape scene that reportedly deeply offended the Mexican Mafia's machismo.
Edward James Olmos was issued a permit to carry a concealed weapon by the Los Angeles Police Dept. because of the many death threats he received from Mexican Mafia members. Before filming began, they were under the impression that the movie was to be a favorable portrait of their organization, and were angered when the film emphasized their criminal activities.
In the prison parts of the movie, Olmos managed to get on screen real-life gang members from the Bloods and Crips, Aryan Brotherhood, Nazi Lowriders, Hell's Angels, 18th Street, White Fence, La Colonia de Watts, Dogtown, East Side Clover and the infamous Black Guerilla Family.
Most of the extras who were dressed as prisoners quit after the first day of filming. They were kept in a gated area next to an open sewer and had to ask guards to use the bathroom. Guards are used to ignoring prisoners, so they mostly ignored extras dressed as prisoners. They weren't given enough water and lunch wasn't served until late in the day. Conditions slightly improved on the second day, but on the third and final day of filming at Folsom Prison there were about 25 of the 200 that showed up on the first day.