Richard Burton was set to play his character from The Wild Geese (1978), Allen Faulkner, but died just days before filming began. Edward Fox stepped in to play Alex Faulkner, the brother of the character played by Burton.
As Rudolf Hess, 77-year-old Laurence Olivier was in poor health during filming and required a nurse to accompany him during production. Olivier was also beginning to suffer with memory problems and labored for hours on his one long speech, despite having trouble with the dialogue.
After Richard Burton had died, producer Euan Lloyd had to re-cast his part. Lloyd contacted Edward Fox who was in the country working on his house. Fox agreed to do the movie so he could add another wing onto his home.
According to Ingrid Pitt's personal website, Pitt, who did not have any scenes in this film with acting legend Laurence Olivier, did however have dinner with him during the shoot, saying that Olivier was "very old and frail by this time but very gallant".
The original film in the series was called The Wild Geese (1978) but for this sequel the word "The" was dropped from the title making the film called Wild Geese II (1985) rather than "The Wild Geese II".
After the success of The Wild Geese (1978) novelist Daniel Carney was asked by producer Euan Lloyd to write a sequel. Carney originally refused has he could not think up a storyline until producer Euan Lloyd gave him one, this film's high-concept: the kidnap of Rudolph Hess from Spandau Prison.
The film's script had been written with Richard Burton in mind for his character. Due to the late death of Burton so close to the start of principal photography, Burton's part could not be re-written bar for the change of the character's name, and as such, actor Edward Fox had to say dialogue which had been written for Burton.
Around a year before this movie was made and released, a similarly titled low-budget Italian-West German film, which appeared to be a sequel to The Wild Geese (1978), had been made and released. It was called "Code Name: Wild Geese" (Code Name: Wild Geese (1984)), and was not a sequel, but a knock-off. Ironically, like The Wild Geese (1978), it had a great lead cast, arguably better than this sequel.
Lewis Collins has said that he was originally hired to play Haddad due to a contract with producer Euan Lloyd. Collins had headlined Lloyd's The Final Option (1982) movie around three years earlier. However, the part was cast with American Scott Glenn. Collins ironically had starred in "The Wild Geese" rip-off movie "Code Name: Wild Geese" (Code Name: Wild Geese (1984)) which may have been a factor in his non-inclusion in this sequel.
No characters from the original The Wild Geese (1978) movie appear in this sequel. Ironically, the film's trailer states "The Wild Geese are back!" and "This time the Wild Geese are flying higher than ever before and further than ever before!". Moreover, one of the film's taglines states, "They fly again...".