According to Paul Marco, Edward D. Wood Jr. thought that Bela Lugosi's memory might not be very good, so for Lugosi's long speech, Wood had the prop man make cue cards. Lugosi, upset, insisted he didn't need cue cards and he would "memorize it." Wood still insisted on the cue cards, telling Lugosi, "We have to be safe". Lugosi went to Marco for help. He had Marco promise not to show him the cue cards during the scene. Marco held the cards at his side the whole time and Lugosi never looked over once. After Lugosi's performance the whole crew got up and applauded.
Tony McCoy was cast as the male lead primarily because his father, Donald E. McCoy, owner of Packing Service Corp. (a meat packing company) and a major investor in the film, insisted that his son get the lead role.
Producer Donald E. McCoy strongly disagreed with the use of nuclear warheads. He only agreed to finance the film if Edward D. Wood Jr. rewrote his original script, and made it end with a nuclear explosion as a warning against the use of nuclear weapons.
In 1980, the book "The Golden Turkey Awards" claims that Bela Lugosi's character declares his manservant Lobo "as harmless as kitchen" [sic]. This allegedly misspoken line is cited as evidence of either Lugosi's failing health or Edward D. Wood Jr.'s incompetence as a director. However, a viewing of the film itself reveals that Lugosi said this line correctly "Don't be afraid of Lobo; he's as gentle as a kitten." An easier explanation would be that authors Michael Medved and Harry Medved saw the film in a theater setting with poor sound quality, and misheard. Unfortunately, the inaccurate claim keeps circulating.
The film uses both stock footage of a real octopus and a fake, rubber octopus in scenes where "the monster" interacts with actors. It is widely believed this is a prop from the film Wake of the Red Witch (1948). Contradictory accounts claim that Edward D. Wood Jr. either stole or rented the prop from Republic Pictures, which produced the earlier film.
The country of origin for Vornoff and Strowski is left unnamed. The only clues are that it is European and has its own dreams of conquest. By implication, the country which exiled Vornoff in the 1930s could be Nazi Germany or the Soviet Union. Strowski uses the term "master race", which is a key concept of Nazism.
The film contains Cold War themes such as agents of foreign powers, nuclear power, and atomic weapons. They were prevalent enough in films of the 1950s and 1960s that some commentators have called them a subgenre in itself.
While this was Bela Lugosi's last speaking role, it wasn't his last film. Lugosi had a silent role in The Black Sleep (1956). Lugosi appeared in Plan 9 from Outer Space (1959) despite dying before filming began; he appears in archive footage from an unfinished film called "The Vampire's Tomb." Lock Up Your Daughters! (1969) was recycled footage from Lugosi's earlier films, possibly mixed with some new material.
Throughout the film, the mute Lobo is implied to have an unspecified intellectual disability and to be of sub-human intelligence. However, he successfully operates complex machinery as if he had been trained to do so.
The opening credits feature the exterior of a house, introducing the location where much of the plot will supposedly take place. It is uncertain whether this opening scene features a real location or theatrical scenery of some sort. Various theories exist, suggesting that the scene features the shot of a matte painting, a rear projection effect, or a miniature effect.
According to Scott Zimmermam, an acquaintance of Edward D. Wood Jr., the mystery about the house depicted in the film had a solution. According to this version of the story, it was a normal two-story house located in a crowded neighborhood of Los Angeles. For the purposes of the scene, Wood reportedly had a canvas tarpaulin erected behind the house to mask the presence of other buildings in the background. The painted canvas created the illusion that the house itself was part of a painting. There are some doubts about his story.
In a subplot, there are storms every night for three months and strange weather patterns. The characters attribute the phenomenon to the effects the nuclear explosions have on the atmosphere. This probably reflects actual anxiety of the 1950s about potential climate change. Until the Partial Nuclear Test Ban Treaty (1963), atmospheric nuclear weapons testing was used widely and recklessly. In the context of the film, the strange weather is implied to be a side-effect of the experiments of Vornoff, which apparently released radioactivity into the atmosphere.
The title "Bride of the Atom", which Vornoff uses for Janet in the bridal dress, is inexplicable unless the scientist is actually attempting to use Janet to replace his long-lost wife. One of his re-assuring lines to Janet concerning the experiment, "It hurts, just for a moment, but then you will emerge a woman . . . " sounds as if he's preparing her for the loss of her virginity.
The reasons Loretta King was cast as the female lead instead of Dolores Fuller are disputed. Decades later, Fuller claimed that King bribed Edward D. Wood Jr. into casting her as Janet with promises of securing further funding for the film (King has vehemently denied this). Fuller wound up with a part in the film, but it was just a short appearance, not much more than a cameo.
The first incarnation of the film was a 1953 script by Alex Gordon titled "The Atomic Monster", but a lack of financing prevented production. Edward D. Wood Jr. revived the project as "The Monster of the Marshes."
The trivia items below may give away important plot points.
Contrary to popular legend, Bela Lugosi cannot be seen fighting the rubber octopus in the sump (filmed in Griffith Park). Close examination of the scene reveals a stunt double doing battle. In fact, all the shots of Vornoff carrying Janet through the brush and moving down the hill, reveal a stunt double for Lugosi. Even the real close-ups of Lugosi during these sequences appear to have been shot on a stage with black backing.
Edward D. Wood Jr. was unhappy with the daillies of Dr. Strowski's death, and asked cinematographer William C. Thompson for advice on how to make the other octopus attacks in the film look more convincing. Thompson told Wood that it would look better if he used a rain machine during the attacks, and had them lit only by lightning strikes, which Wood employed in the remaining attack scenes. Due to budgetary constraints, however, there was no time to refilm Strowski's death scene.