Edward Fox had known General Horrocks before working on the film, and considered him a friend; thus, Fox took great care to portray him accurately. Years later, he would cite his portrayal of Horrocks as his favorite film role.
During WWII, Dirk Bogarde, who played Lt. Gen. Browning, served in intelligence with the British army. He and eight other intelligence officers were sent to Arnhem by Bernard L. Montgomery during the battle.
Denholm Elliott who has a brief cameo as an RAF Officer actually did serve in the RAF during World War II.
One Steve Limit: The intelligence officer called Major Fuller in the film was actually called Brian Urquhart. However since Sean Connery's character, the commander of the British airborne division was also historically named Roy Urquhart it was decided to rename the more minor character played by the unknown actor.
Real-Life Relative: Gerald Sim (Colonel Sims) was the brother-in-law of the director Richard Attenborough.
Roger Moore was initially cast as Lt. Gen. Brian Horrocks, but was unable to appear when problems surrounding the Bond franchise meant that The Spy Who Loved Me was made a year later than originally planned, therefore coinciding with the production dates. In addition, Horrocks had approval over the character and turned Moore down, and the role instead went to Edward Fox (who nailed it).