In May '62, while filming, Jeanne Moreau suffered a slight nervous breakdown due to the stifling atmosphere of the film.
Orson Welles reportedly dubbed a few lines of Anthony Perkins dialog. Perkins later said he could never figure out which lines they were.
Orson Welles told Peter Bogdanovich in "This Is Orson Welles" that "there's not a single symbol" in "The Trial".
"The Trial" is based on the Franz Kafka novel of the same name. Orson Welles also includes a shorter Kafka parable, "Before the Law," in the pin-screen opening to the movie.