Soviet agent Rudolf Ivanovich Abel sent and received coded messages that were hidden inside such things as hollow U.S. coins, bolts, and batteries. The FBI first became aware of Abel's activities in 1953, when Abel's incompetent junior colleague Reino Hayhanen carelessly spent a hollow nickel that ended up in the hands of a paperboy. The Brooklyn newsboy who got the nickel thought it felt too light. He dropped the nickel on the sidewalk, and it popped open, revealing a piece of microfilm with a coded message inside. After Hayhanen's blunders, Abel lost confidence in him and sent him back to the U.S.S.R., which would not have gone well for Hayhanen, who defected in 1957. He showed the FBI how to crack the code and it was Hayhanen who gave up Rudolf Abel. The "Hollow Nickel Case" was also dramatized in Sono un agente FBI (1959).
For the scene outside the courtroom, the photographers were initially instructed to put their used flashbulbs, which are extremely hot to the touch, in their pockets. One of the background actors happened to be the historian of the New York Press Photographers Association. He told executive producer and first assistant director Adam Somner that, at the time, photographers would have ejected the bulbs onto the floor. After several takes, noticing the bulbs strewn across the floor, Steven Spielberg decided to shoot the low-angle view of the principals walking through them.
In an interview with the International Spy Museum, the son of Francis Gary Powers, Francis Gary Powers, Jr., indicated that his father was not told to commit suicide if shot down, unlike the depiction in the movie. Instead, it was given as an option in case physical torture had been involved, allowing the pilots to use a poison pin if the pilots chose to commit suicide. He also indicated that the Soviets found the pin on a third strip search, but Powers warned them not to touch it. The Soviets tried the pin on a dog and the dog died a few moments later.
For six days of shooting on the Glienicke Bridge and surrounding streets, the production firm had to pay 10,552.13 EUR (about $11,428.96 U.S.) to the local district, the city of Potsdam, and the German government. It took one person five months to get the all the necessary permits from 23 different agencies.
According to Steven Spielberg in a press release for the movie, Gregory Peck came after the story in 1965. Alec Guinness agreed to play Rudolf Ivanovich Abel, Peck would play James B. Donovan, and Stirling Silliphant would write the script. MGM declined to make the movie at the time. It was 1965, Cold War tensions were high, and Metro-Goldwyn-Mayer was reluctant to get into the politics of the story.
Steven Spielberg: [trademark recognition] In two separate scenes, multiple commuters on the train reading stories of the trial of Rudolf Ivanovich Abel look up from the story and recognize James B. Donovan, some looking over the top of their newspapers at him, some glancing up from their newspapers. Similarly, in Minority Report (2002), a commuter on the train reading a newspaper with the story of the hunt for John Anderton looks over the top of his newspaper and recognizes Anderton.