Montgomery Clift had a habit of cutting his hair very short when he was between films and would not work until it had grown back. In fact, his scene in this film was shot right after getting one of those haircuts. He also had so much trouble remembering his lines, the scene had to be re-shot many times. Director Stanley Kramer finally gave up and told Clift to ad lib his lines, saying that this would help to convey the confusion in his character's mind while he was being questioned on the witness stand. "Monty seemed to calm down after this," Kramer later recalled. "He wasn't always close to the script, but whatever he said fitted in perfectly, and he came through with as good a performance as I had hoped."
Marlene Dietrich had a great deal of trouble performing in the scene between Mrs. Bertholt and Judge Haywood when she claims German civilians did not know of the atrocities the Nazi government committed during the war. Dietrich, who, during the war, had worked for the Allies against the Nazis, found the sentiment so repulsive, she could not keep her concentration. Only after counseling by Spencer Tracy was the actress able to complete the scene. According to an interview with her grandson Peter Riva on the Icons Radio Hour, Marlene would get physically ill (to the point of vomiting) in the evenings over this part. In a conversation with her daughter Maria, Maria told her to "simply play her mother". The fictional Mrs. Bertholt is a representation of the mother of Marlene Dietrich.
A stage adaptation, also written by Abby Mann, was produced on Broadway many years later. It starred Maximilian Schell in a different role, this time as Ernst Janning, the role played by Burt Lancaster in the film. The play opened at the Longacre Theatre in New York on March 26, 2001 and ran for 56 performances.
Marlon Brando wanted to play the role of Hans Rolfe, the German lawyer who defends the German judges. Brando, in a rare attempt to garner the part, actually approached Stanley Kramer about it. Although, Kramer and Abby Mann were very intrigued with the idea of having an actor of Brando's talent and stature in the role, both were so impressed with Maximilian Schell's portrayal of the same part in the original Playhouse 90 TV broadcast of "Judgment at Nuremberg", that they had decided to stick with the relatively unknown Schell, who later won the Oscar for Best Actor for that role.
The song whose meaning Mrs. Berthold explains to Judge Haywood when they walk past a pub while people in there sing it, is called "Lili Marlene". The song was popular with German and British force during the war, and was actually recorded by Marlene Dietrich herself in the 40s and 50s.
Burt Lancaster does not utter a single word in the courtroom until his outburst roughly two hours and 15 minutes into the film. However, prior to that he does speak briefly in three scenes set in the prison.
Werner Klemperer, who played defendant Emile "nasty Nazi to the very end" Hahn, is probably known better as Col. Klink in Hogan's Heroes. Werner, a Polish Jew, and his family fled Poland at the outset of the Nazi regime. He wound up in Hollywood, and agreed only to play the role of a Nazi in a movie or TV series if the character was despicable, as in this movie, or always bumbled and was a loser, as in Hogan's Heroes.
Immediately upon hearing his sentence, Emil Hahn (Werner Klemperer) declares, "Today you sentence me; tomorrow the Bolsheviks will sentence you!". Whether intended or not, those words strongly parallel the last words of the notorious Julius Streicher as he was about to be hanged following his conviction at the first Nuremberg Trial. As the black hood was placed over his head, Streicher screamed, "The Bolsheviks will hang you one day!"