Credit for directing this film was given to James Cameron. Most of the work was actually performed by Ovidio G. Assonitis, the film's producer and prolific film-maker. Assonitis was dissatisfied with Cameron's progress after the first week and took over. According to "Dreaming Aloud," a biography of James Cameron by Christopher Heard, Cameron did do the shooting for this movie, but was not allowed to see his footage and was not involved in editing. He broke into the editing room and cut his own version, but was caught and Assonitis re-cut it again.
It was during the Rome release of this movie in which James Cameron grew ill and had a dream about a metallic torso dragging itself from an explosion while holding kitchen knives, which gave Cameron the idea for The Terminator (1984).
James Cameron described his creative process as "what I'm good at is working with actors to create scenes and then editing their performances to get the absolute best vibrating version of that scene and then share that with the audience. It's an amazing process to go through. Sometimes you think it's not going to work when you get started and then the characters come to life."
According to Lance Henriksen, making this movie was the most trying time in his life production-wise. The film's European producer Ovidio G. Assonitis wanted to spend only 300.000 dollars on the film, which meant that they had to cut cost wherever they could. Replacement director James Cameron even had to make a number of the flying piranha rubber models himself. Henriksen was told that they can't afford a uniform for his character and that he should play the role in his own plain clothes to which Henriksen objected insisting that a harbor patrolman can't do his job without a uniform as if he's some plain clothes undercover cop. The situation was resolved when Henriksen noticed a sharp dressed waiter the same size as him and asked him to buy his uniform for 75 bucks of his own money. He also had to use whale-shaped pins as his police badge and epaulets that show his rank. Additionally, Henriksen had to carve the wooden gun in his holster by himself. Cameron wanted an explosive finale, so he added to the the script that Henriksen's character jumps out of a helicopter to save his drowning family. The helicopter was a Jamaican police helicopter used to chase drug smugglers and was piloted by a professional pilot. A boat snuck under the chopper at one point almost hitting Henriksen's legs, so the pilot had to raise the chopper quickly and, in the maneuver, Cameron accidentally dropped the shooting camera into the sea, which was never recovered. Both Cameron and Henriksen considered themselves lucky to still be alive after that. Additionally, during his scripted jump, Henriksen almost broke an arm and his boots immediately started filling up with water as soon as he landed, so he almost drowned. The original director of the film was Miller Drake, who started his career in Roger Corman movies just like James Cameron. Producer Assonitis send Drake's version of the film to Warner Bros. who didn't like it and decided not to distribute the film. Assonitis decided to immediately fire Drake and hire Cameron to reshoot and reedit the movie. Henriksen thinks that the fact that Warner Bros. accepted Cameron's version of the film was a clear sign that Cameron was an outlier with big future in the movie business. Drake and Cameron would later work together again on movies like Terminator 2.
As of 2017, this is the only fictional feature film James Cameron has directed that does not have a title starting with the letters A or T. His only other theatrical film with a similar distinction is his IMAX documentary Ghosts of the Abyss (2003).