The captioner decided to have some fun with Prince Koura's lines. The first time Koura says his unintelligible magic spells to summon the dark spirits against Sinbad and his crew, the captions read, "SSFUP AOCOC ROF OOKCUC MI", which is "IM CUCKOO FOR COCOA PUFFS" spelled backwards. The next time, the captions say "TTIBBAR YLLIS. YLNO SDIK ROFERA XIRT", which is "TRIX ARE FOR KIDS ONLY. SILLY RABBIT." backwards.
Robert Shaw desperately wanted the role of Sinbad, but was placated by being cast uncredited as the Oracle. His face was heavily swathed in make-up and his voice electronically altered by a sound engineer. Shaw was paid £5000 for just one day's work.
Ray Harryhausen paid tribute to one of his inspirations, The Thief of Bagdad (1940), with this film. Both had the same composer, and Kali's dance copies many moves of the six-armed robot in the 1940 film. The Hindu-style temple in the 1940 film is echoed in the Hindu-style carvings of Lemuria, and the look of the Lemurians is based on the 1940 film as well; there are other echoes and influences to be seen by those familiar with both films.
The Griffin, which fights the One-Eyed Centaur, was originally going to be a Neanderthal man, according to Ray Harryhausen's early concept art for the project (illustrated in charcoal pencil). The "Neanderthal man" concept would later be realized into the Troglodyte in Sinbad and the Eye of the Tiger (1977).
When Sinbad and the others land on Lemuria, a cliff along the left side of the beach is covered with carvings. According to an interview given by Ray Harryhausen, the cliff doesn't exist. The scene was shot on a popular beach in Spain, and the cliff is a matte painting added to hide all the spectators.
A "Valley of the Vipers" sequence was devised by Ray Harryhausen. This would have featured both real snakes and giant animated snakes. However, this sequence was unused, as producer Charles H. Schneer was afraid of snakes (and argued that the scene would upset pregnant women).
Orson Welles was initially cast as The Oracle, but his agent asked for an extremely high fee for the expected three days of voice work. Robert Shaw, who was on vacation in Spain, did the work in one day.