A colorized version of this film was released on VHS in 1994, the fiftieth anniversary of the invasion.
A number of sources credit Christopher Lee and Geoffrey Bayldon as being in this project but Lee denies working on the film and Bayldon is nowhere to be seen in the final print.
According to fellow veterans major Werner Pluskat was not at his command bunker in Omaha Beach when the first wave of the invasion forces landed, instead he was in a bordello in Caen.
Adolf Hitler doesn't make an appearance in the film. In reality, he slept through the start of the D-Day landings, having taken a sleeping pill.
Alongside the three credited directors, Gerd Oswald directed the parachute drop scene and Darryl F. Zanuck himself did some pick-ups.
Although the screenplay is credited to Cornelius Ryan, many other writers worked on the film.
An estimated 23,000 troops were supplied by the U.S., Britain and France for the filming. (Germans only appeared as officers in speaking roles.) The French contributed 1,000 commandos despite their involvement in the Algerian War at the time.
As a 22-year-old private, Joseph Lowe landed on Omaha Beach on D-Day with the Second Ranger Battalion and scaled the cliffs at Point-Du-Hoc. He scaled those hundred-foot cliffs all over again, for the cameras, some 17 years later.
As part of John Wayne's contract, in addition to his high fee, he demanded he received separate billing. Usually in film credit this would mean them starting off with "Starring John Wayne and.... the other actors" however the credits begin with "starring *the other actors*... and John Wayne" Wayne's name appears last on the credits, while still meeting the separate billing clause of his contract. Many of the other cast (who had actually taken part in D-Day and WW2) held Wayne's refusal to join up during the war with some disdain.
As there was a nudist colony two miles inland from the Corsican beach, it was necessary to post signs warning the colonists not to approach the water during filming.
As would be done again later in the WWII epic, Patton, the Twentieth-Century Fox logo is never shown onscreen in this film.
Average Shot Length = ~8 seconds. Median Shot Length = ~6.5 seconds
Colonel Benjamin Vandervoort was very disappointed to find that he was being played in the movie by John Wayne, since even 17 years after D-Day Vandervoort was still a decade younger than the 54-year-old Wayne.
Despite being in two scenes Gert Fröbe never actually says a word.
Despite being one of the more lengthy cameos it only took four days to shoot John Wayne's major cameo.
Despite the Cornelius Ryan connection, the only stars to appear in both this film and A Bridge Too Far are Sean Connery and Wolfgang Preiss.
Due to the massive cost overruns on the film Cleopatra (which was filming contemporaneously), Darryl F. Zanuck had to agree to a fixed filming budget. After he had spent the budgeted amount he started using his own money to pay for the production.
During shooting in Ste. Mère-Eglise, traffic was stopped, stores were closed and the power was shut down in order not to endanger the paratroopers who were unused to night drops in populated areas. Still, the lights and staged fire proved too difficult to work around, and only one or two jumpers managed to land in the square - with several suffering minor injuries. One of the initial jumpers broke both legs in landing. Ultimately, plans to use authentic jumps were abandoned, opting instead for rigged jumps from high cranes.
During the filming of the landings at Omaha Beach, the American soldiers appearing as extras didn't want to jump off the landing craft into the water because they thought it would be too cold. Robert Mitchum, who played General Norm Cota, finally got disgusted with them and jumped in first, at which point the soldiers had no choice but to follow his example.
During the making of the film, Darryl F. Zanuck effectively commanded more "troops" than any of the generals during the actual campaign.