For the scenes in the underwater mermaid kingdom, Douglas Fairbanks had the cameras shoot through a curtain of thin gauze, to give the illusion that the Thief was swimming underwater. The mermaid kingdom scenes were then tinted blue in post-production.
For the early scene where the Thief leaps in and out of the giant clay pots in the marketplace, Douglas Fairbanks had small trampolines placed inside each pot, allowing him to bounce easily from pot to pot.
The production's cost has been commonly cited as $2 million or $2.5 million for decades. Douglas Fairbanks' biographer Jeffrey Vance, who had access to Fairbanks' private and professional papers, revealed for the first time in 2008 that the film actually cost much less: $1,135,654.65. See "Douglas Fairbanks" (UC Press, 2008), page 153.
Ranked #9 on the American Film Institute's list of the 10 greatest films in the genre "Fantasy". It is also one of only two silent films chosen for the AFI's "10 Top 10" lists (the top 10 films in 10 genres) in June 2008; the second was City Lights (1931).