El coloso de Rodas (1961) is set during the time following Alexander the Great's death (323 BC) but before the rise of the Roman empire (27 BC), known as the Hellenistic era. Most sword-and-sandal epics of the 1950s and 1960s were set in either classical Greece or even earlier (Le fatiche di Ercole (1958), Ulisse (1954), El gigante de Maratón (1959)) or the later Roman period (Ben-Hur (1959), Il magnifico gladiatore (1964), Quo Vadis (1951)). The only other films made during the peplum era to use a Hellenistic setting are Anibal (1959), La venganza del rebelde (1960) and El sitio de Siracusa (1960).
El coloso de Rodas (1961) was Sergio Leone's first work as a credited director, in a genre where he already had worked before (as the replacement director for Los últimos días de Pompeya (1959) and as a secondary director for both Ben-Hur (1959) and Quo Vadis (1951)). It is perhaps the least known of the seven films he officially directed, and is the only one without an Ennio Morricone score.
During most of his scenes, Rory Calhoun wears a wide bracelet on his left arm and stiffly extends it covered by a cloak. According to Sergio Leone scholar Christopher Frayling and Calhoun's widow, the actor did that to hide some 20th-century tattoos.
The real Colossus, one of the Seven Wonders of the Ancient World, is said to have been approximately 32 meters high. The cinematic version stands 110 meters and its legs bestride the harbour. The actual location of the original colossus is still debated. The fortress at the entrance of the harbour is cited as one possible location with the Acropolis of Rhodes on a hill overlooking the harbour cited as another. Scholars generally agree, however, that anecdotal depictions of the Colossus straddling the harbour's entry point have no historic or scientific basis.
Rory Calhoun, who was in Italy for the title role in MGM's Marco Polo (1962), stepped into the lead role of "Colossus" on only one day's notice. He initially arrived at 11:30 on the first day he was to start filming. According to the biographer Christopher Frayling of Sergio Leone, Calhoun's first day included an accidental fall into a swimming pool.