David Opatoshu's character Akiva Ben Canaan, commander of the Irgun, is based on the real-life Menachem Begin who later became prime minister of Israel. Opatoshu portrayed Begin in Raid on Entebbe (1976) (TV).
250 extras were hired to play escaping prisoners at the old prison in Acre. However, 253 people were counted as escaping, those three extra escapees were actual escaped inmates from a mental ward near the set.
At the film's premiere, as the movie neared its third hour with the end not yet in sight, comedian Mort Sahl stood up from his seat in the packed theater and shouted, "Otto, let my people go!" The incident quickly became a popular piece of Hollywood lore.
Director Otto Preminger helped to end the stigma of the Hollywood blacklist by hiring Dalton Trumbo to adapt the screenplay for the film
Sal Mineo actively sought the role of Dov Landau despite being told that he did not look Jewish or anything like the character.
When the filmmakers bought the ship that they used as the refugee ship, the company they bought it from was so thrilled that they delivered it with a fresh coat of paint. Unfortunately, this was unsuitable, since the ship was meant to look old, so fake rust had to be painted on at great expense.
Although many critics felt that Paul Newman was miscast as Ari Ben Canaan, director Otto Preminger maintained that he had envisioned only Newman playing the part from the time he read the novel.