Although the feature was promoted as "All Technicolor", in actuality, only 7234 of its original 8569 feet were filmed in color. Most of the underwater sequences were filmed in B&W and tinted green, in the usual fashion of the 1920s, and some shots of explosions were enlivened by using the Kelley Color/Handschiegl spot-coloring process.
Possibly the first talking, and first color, feature-length science fiction movie. It is partially silent and partially monochrome as it was made.
According to an article in the original "Famous Monsters of Filmland" magazines, production was actually started in 1926. There were various problems, including weather and the advent of talkies, which slowed/halted production several times before the film was finally completed and released three years later. The article included stills showing the original 1926 undersea denizens and the redesigned version which actually appeared in the film.
Although the entire film has always been available in black and white prints, film historians long believed that no complete color print of the film had survived - until 2013 when experts from the George Eastman House in the US discovered that such a print had been preserved in the Czech National Archive. Until this discovery, it was thought that the only surviving Technicolor fragment of the film was a 10-minute reel reposing in the UCLA Film and Television Archive.
At least two prominent members of the supporting cast, Robert McKim (who died in June 1927) and Edward Connelly (who died in November 1928), were no longer around by the time the film was finally released, and for that reason, their names do not appear on screen.