The cast includes real inmates of Rahway State Prison, which is also known as East Jersey State Prison, and is located in Rahway, New Jersey. Some of the prisoners appear as extras and background artists in the movie.
Chuck Wepner, the real-life inspiration for Rocky (1976), was an inmate at the prison where the film was shot. Sylvester Stallone greeted Wepner and told the other inmates that Wepner was "the real Rocky".
Director John Flynn has said of this movie, in a 2005 interview with Harvey F. Chartrand for Shock Cinema: "Lock Up (1989) is a strange lesson in how Hollywood movies are made. Stallone had a 'window' which means the guy was available for a certain window of time. Larry Gordon [Lawrence Gordon] had a terrible script set in a prison. Stallone calls James Woods and asks if I'm any good as a director. Woods says yeah, he's a good director and you ought to work with him. So we have a director and a star, but no script. All we have is a theme - a guy escaping from prison. So we hire Jeb Stuart, who was then one of the hottest writers in Hollywood, to rewrite the script and we go off looking for prison locations. Now we have a star, a theme, a shooting date, a budget, a studio, but we still have no script. So we all go back to New York City, and move into a hotel where Larry 'tortures' Jeb and Henry Rosenbaum into writing a script in record time. Meanwhile, I'm going around scouting prisons. We finally found one in Rahway, New Jersey. Jeb and Henry were writing the script as we were making the movie. New pages would come in every day. There was one day when I was on the third tier of a cell-block in Rahway Penitentiary and I had nothing to shoot. I had my movie star, all these extras and a great location - and the pages were on their way. So we sat around and bullshitted with the prisoners. Stallone is a smart guy and a very underrated actor. If I ever needed a better line, he'd come up with one. Stallone is a really hard worker. I had no problem whatsoever with him".
The brief dance done by Eclipse (Frank McRae) when he scores the touchdown during the football game resembles the "Ickey Shuffle" made famous by Elbert "Ickey" Woods [Ickey Woods aka Elbert Lee Woods] who played fullback for the Cincinnati Bengals in the late 1980s.
Sylvester Stallone originally created a character named "Chink Weber" for Rocky II (1979) who was to be played by Chuck Wepner. But the character was deleted from the script. Stallone reused the "Chink Weber" name for the script for this film with the part being played by Sonny Landham.
The name of the penitentiary in the film was the fictional jail called "Gateway Prison". It was portrayed by the real life East Jersey State Prison situated in Rahway, New Jersey. The facility is also known as the Rahway State Prison.
Some of the production got locked-in during the filming of Lock Up (1989), when the inmate count numbers didn't add up at the end of the day, so numerous cast and crew got delayed in the prison until around 7:30 p.m., until the calculation was correct.
The majority of the guards acting as extras, actors and background artists in the movie were real-life guards from Rahway State Prison used for the film which is now known as the East Jersey State Prison (EJSP). The guards were paid the standard Screen Actors Guild (SAG) daily rate at the time of 93 dollars per day for playing their profession.
According to the article "15 Things You May Not Have Known About 'Lock Up (1989)'" at the website Mental Floss, "each morning, director John Flynn had the producers hand-select 200 of the prison's 1,900 inmates to work from 7:30 a.m to 5 p.m. that day. The production reportedly provided the lucky inmates with donuts and coffee each day-luxuries they weren't normally allowed". The actual real-life prisoner extras and background artists were paid a minimum daily wage of 26 dollars per day.
Playing Frank Leone, Sylvester Stallone also played a character called Frank in the earlier movie Capone (1975) as the character Frank Nitti, and similarly in Avenging Angelo (2002), as the character Frankie Delano. Stallone also played Frank the Repairman in two episodes of the television series Las Vegas (2003).
The movie was scored by Bill Conti who had composed the Oscar nominated music score for Sylvester Stallone's Rocky (1976). Lock Up (1989) is one of around ten collaborations of the pair and one of just a handful of non-Rocky franchise films scored by Conti and starring Stallone with the others being F.I.S.T. (1978), Victory (1981) and Paradise Alley (1978).
The production scouted for prison locations for several months and visited eight maximum security prisons, of which in the end, the jail setting used for the film was decided to be East Jersey State Prison in Rahway, New Jersey.
The movie was nominated for three Golden Raspberry Awards at the 10th annual ceremony including Worst Picture, Worst Actor - Sylvester Stallone and Worst Supporting Actor - Donald Sutherland, but the film failed to take home a Razzie in any category.
Robert Vazquez portrayed Officer Vazquez, who has the same last name as his own. Vazquez was also a technical consultant to the production, being also billed in the closing credits as a prison advisor.
The trivia item below may give away important plot points.
The film could have been a "Rambo" film. If it had been a "Rambo" film, it would had taken place after First Blood (1982). Rambo (Stallone) is tried and convicted for his rampage in Hope, Washington, sent to Gateway Prison, and is physically abused by the sadistic guards. Warden Drumgoole decides to set up Rambo by having him attempt to escape from prison, so that Rambo would receive a ten-year sentence. By using Dallas, Rambo is pushed too far, fights the guards, and goes after Drumgoole.