The filming of a battle scene was stopped in order for the company to watch while overhead a group of British fighters attacked a formation of German bombers on their way to bomb London. When the real battle passed out of sight, the movie battle resumed filming.
As a tribute to his abilities as a director, and uncertain over his own unproved directing abilities, Laurence Olivier originally invited William Wyler, who had directed Olivier in Wuthering Heights (1939), to direct. It was Wyler whom Olivier always credited with teaching him how to give a more subtle performance in films and with giving him more respect for the art of acting in film. Wyler, however, declined, saying, "If it's Shakespeare, it must be you [who directs the film]". Carol Reed and Ralph Richardson told him the same thing.
Many of the sets used for scenes in France (not including the battle scenes) are based on medieval illustrated texts such as the "Très Riches Heures du Duc de Berry". The producers attempted to recreate the flawed perspectives and stylised architecture, leading to a distinctly unrealistic look to the sets.
Laurence Olivier's then wife, Vivien Leigh, very much wanted to play Katherine, but David O. Selznick would not let her out of her contract with Selznick International Pictures, feeling that the role was much too small for an actress of her cache. Leigh never forgave Selznick, and never worked for him again.
The majority of the film, including the Battle of Agincourt, was filmed in Ireland where cast and crew could be safe from nightly Luftwaffe raids (Ireland was a neutral country in the Second World War).
Due to the absence of trained stunt men, Laurence Olivier had to do his own stunts as well as showing almost every Irish extra how to do their stunts (this resulted in him suffering many injuries including fractured shoulders).
Laurence Olivier agreed not to appear in a film for 18 months to encourage this one to attract as large an audience as possible and in return was paid £15,000 tax-free, about £460,000 in today's money.
When Vivien Leigh, originally slated to play Katherine of France, was forced to give up the role, Renée Asherson replaced her because she was exactly the same size as Leigh and therefore the costumes didn't have to be altered to fit her.
The only lines in the film not written by Shakespeare are spoken by Pistol at the end of the Boar's Head scene: "Farewell, farewell, divine Zenocrate/Is it not passing brave to be a king/And ride in triumph through Persepolis!" They are from "Tamburlaine the Great" by Shakespeare's contemporary, Christopher Marlowe.
Princess Katherine was approximately 14 years old at the time of The Battle of Agincourt, however, Renée Asherson was approximately 29 years old at the time of production of the film, more than twice the age of the real life character Asherson was portraying.
Max Adrian, who portrayed Louis The Dauphin was 41 years old at time of production, while the real life character he portrayed was only 18 years old on October 25, 1415, the date of the Battle of Agincourt.
The full title of the play as first published in the "First Quarto" text (August 1600) was: "The Cronicle History of Henry the Fift with His Battell Fought at Agincourt in France. Togither with Auntient Pistoll" The full title as rendered on the title card at the beginning of this 1944 film production was: "THE Chronicle History of KING HENRY THE FIFT with his battell fought at Agincourt in France BY Will Shakespeare"
As a secondary title card, the 1944 film shows: "will be played by The Lord Chamberlain's Men AT THE GLOBE PLAYHOUSE THIS DAY The FIRST of May 1600" Title page of the August 1600 edition of Shakespeare's Henry V, often called the "Bad Quarto" was printed as follows: "As it hath bene fundry times playd by the Right honorable the Lord Chamberlaine his fervants." (bene = been, fundry = sundry, playd = played, fervants = servants)
Although this film was based on a work of fiction, the play it was derived from was based on historical facts, and of the 37 credited characters, at least 16 were real people, known to exist as notable historical figures.
The film was shot on location at the Powerscourt Estate in Enniskerry, County Wicklow, Ireland. Many of the interior sets and some of the exterior sets were constructed at Denham Studios, Buckinghamshire, UK. Those sets were based on illustrations made or commissioned by one of the 16 historical real people (above) in Shakespeare's Henry V, John, Duke of Berry (referred to only as the Duke of Berry in the play), in his catalogue of illustrations, "Très Riches Heures du Duc de Berry."
The availability of extras for the battle scenes was one of the main reasons why Laurence Olivier decided to film the Agincourt sequence in Ireland. Due to the war, there was a huge shortage of able bodied men in the UK. Irish civil servants were offered time off to work on the movie.
Part of the reason Ireland was chosen as a location was that it was a neutral power during World War II, thus outdoor shooting would not be disturbed by aerial warfare. However, there was one day during which the imaginary war had to be put on hold as an RAF squadron flew overhead on their way to battle.
Esmond Knight, who plays the patriotic Welsh soldier Fluellen was a wounded veteran of the war. He had been badly injured in 1941 while on active service on board HMS Prince of Wales when she was attacked by the Bismarck, and remained totally blind for two years. He had only just regained some sight in his right eye.