Pg. 96 of Steve Martin's memoir 'Born Standing Up', relates a story in which Trumbo's daughter tells Martin: "He's got a screenplay due in four days and he hasn't started in yet." This is in reference to her father writing 'The Fixer' at the last minute.
The film was made in Hungary, then a Communist satellite country. The cast and crew were obliged to work six days a week under considerable pressure, and director John Frankenheimer was very unpopular. Dirk Bogarde always referred to him thereafter as "Frankenstein", whilst Ian Holm reported in his memoirs of nearly forty years later that the director had had, during filming, a very obvious extra-marital affair with the daughter of screenwriter Dalton Trumbo, even though his wife, Evans Evans, was in attendance.