According to the book "Australian Film 1900-1977: A Guide to Feature Film Production" by Andrew Pike and Ross Cooper, the Chauvels (Elsa Chauvel and Charles Chauvel) spent a year doing research and writing the film's screenplay before raising finance for the film from Hoyts Theatres, R.K.O. Radio Pictures and the Commonwealth Film Laboratories.
The film's dedication and opening prologue states: "For eight months at Tobruk in 1941 fifteen thousand Australians and eight thousand British and Indian troops held a German army seven times their number and in seven time their armour. The Germans, understanding machines, but not these men, flung an insult to them in a name - "The Rats of Tobruk." This insult they carried on their bayonets right into the ranks of the oncoming German hordes. It has become one of the finest epitaphs of the war. To these men who could never be driven from their firing posts before Rommel, we pay homage - - "THE RATS OF TOBRUK"."
Exteriors included a large set built at Camden, New South Wales, Australia which portrayed a war damaged street in Tobruk, Libya, North Africa whilst desert scenes including desert battles were filmed at the sand dunes of Cronulla, New South Wales, Australia. End film scenes set in Papua New Guinea were filmed in the South of Queensland, Australia.
The name "The Rats of Tobruk" of the film's title refers to the World War II soldiers, mostly Australian, who held-out against Rommel's Nazi Afrika Corps at the North African Libyan port of Tobruk during 1941. This was during the so-called Siege of Tobruk which began on 10th of April 1941 and concluded in November of that year. The Rats of Tobruk held out for a massive two hundred and fifty days before being they were relieved by more Allied British forces.
The Australian troops who were stationed at Tobruk in 1941 were from the Australian 9th Division and the 18th Brigade of the Australian 7th Division and were under the command of Lieutenant General Leslie Morshead.
During the Siege of Tobruk in 1941, Australian soldiers started calling themselves "The Rats of Tobruk" after German Nazi Radio Berlin described them as "caught like rats in a trap". Moreover, Lord Haw-Haw (i.e. the English language propaganda radio program, Germany Calling) similarly described them as the "poor desert rats of Tobruk."
Legendary Australian actor Chips Rafferty appears in this movie as Milo Trent. About a decade later, Rafferty would appear playing Sergeant 'Blue' Smith in another movie featuring "The Rats of Tobruk" with Richard Burton entitled The Desert Rats (1953).
According to the book 'Bill Collins' Book of Movies' by Bill Collins, the film was " . . . released late in 1944, [and] was a timely, authentic tribute paid by an Australian patriot to the durability and heroism of the AIF [Australian Imperial Force] in the Middle East. The director [Charles Chauvel] and his wife, Elsa [Elsa Chauvel] based their screenplay on material supplied by General Morshead and men who endured the siege. The film was made with the co-operation of the Departments of Information and the Army."
This movie utilizes a narrative technique which features narration in a fictional film spoken by a character that has already died. The dead narrator character was utilized in this film six years before it was used in Billy Wilder's Sunset Blvd. (1950).
Some of the German tanks in this film are actually mocked-up Sentinel tanks from a canceled Australian cruiser tank project; their appearance in this film represents the only time Sentinels were ever used outside of testing.