In John Riley's first scene as a San Patricio, he asks their names to other Irish soldiers. When he asks his name to James Kelly, Riley asks him if he has any experience, and Kelly answers that he has been in His Majesty Royal Artillery. Riley replies with, "Good experience, but there is no royalty here", to what Kelly answers, "Yes, sir". Kelly is played by Prince Albert of Monaco, a member of the Royal family of Monaco.
This was the last film ever released by Orion Pictures.
Annually, the town of Clifden, Connemara, Ireland flies the Mexican flag, in honor of John Riley, born in the town, and the men of the San Patricio's Battalion.
Started production in 1997 under Orion Pictures. During production, Orion was bought by MGM. After considering to send it straight-to-video, MGM ultimately gave the film a limited theatrical release in 1999 thanks to an Internet campaign launched by fans of Tom Berenger. In a 1999 interview, Berenger believed that MGM wanted to bury the film because they had inherited it from Orion and only wanted to focus on distributing its in-house slate.
The film took 30 years for the film to finally get made. The script was originally written in the late-1960s, and was going to be directed by John Huston, but no studio wanted to finance it due to fears that the subject matter would be perceived by the public as "anti-American." Huston died in 1987, and writer Milton S. Gelman would pass away three years later. The film finally got funding in 1997, with Lance Hool, a protege of Huston's, in the director's chair.