The horror movie technique of slowly building tension to a jarring shock which turns out to be something completely harmless and benign became known as a "Lewton bus" after a famous scene in this movie created by producer Val Lewton. The technique is also referred to as a a "cat scare" as off-screen noises are often revealed to be a startled harmless cat.
Near the end of filming, two units were shooting around the clock to speed completion of the film. During the night, one unit would film the animals for the Central Park sequence, while during the day, the other unit would be working with the actors.
Supervisor Lou L. Ostrow was so dissatisfied with the style of the movie he wanted to replace director Jacques Tourneur after four days of filming. Producer Val Lewton got studio head Charles Koerner to reinstate Tourneur, and when Ostrow insisted on the panther appearing in the drafting room sequence, Lewton had Tourneur use low lighting putting the panther in the shadows.
R.K.O. gave Val Lewton only $150,000 to make the film, resulting in "creative" producing. This forced many of the scenes requiring special effects to be done in shadows which many believe increased the suspense of the film. When studio execs insisted that more footage of the panther be included in the movie, Lewton was able to maintain the budget and the suspense of the film by limiting how many scenes the panther could be visibly seen and told the cinematographer to "keep the panther in the shadows." Thus the panther was only visible in the office and zoo cage.
Val Lewton came very close to being fired after only three days of shooting. Lou L. Ostrow, the head of RKO's B-unit, had looked at the first three days of rushes and was not happy with what he saw. Ostrow wanted Lewton out, but was ultimately overruled by RKO chief Charles Koerner who was happy with Lewton's work and wanted him to continue.
Val Lewton originally wanted to adapt Algernon Blackwood's short story "Ancient Sorceries". However, since the story is set in a French village in the nineteenth century, the costume and set costs would have gone over budget, and went for an original story set in modern times. Some elements of Blackwood's short story served as inspiration for Irina's backstory in Serbia.
In her scene, Elizabeth Russell is very reminiscent of the later, TV series original cat woman, Julie Newmar. Interestingly enough, Russell's part is credited as "The Cat Woman". It leaves to wonder whether the Batman (1966) producers were indeed inspired by this lady when casting their own similar role.
Several actors in studio records and casting call lists did not appear in the movie. These were (with their character names) George Ford (Whistling cop), Leda Nicova (Patient), and Bud Geary (Mounted policeman).
This film's initial television presentation took place in Hartford CT Friday 2 March 1956 on WGTH (Channel 18), followed by Memphis Monday 26 March 1956 on WHBQ (Channel 13), Los Angeles Saturday 2 June 1956 on KHJ (Channel 9), New York City Saturday 1 September 1956 on WOR (Channel 9), Altoona Saturday 15 September 1956 on WFBG (Channel 10), and Philadelphia Tuesday 30 October 1956 on WFIL (Channel 6). This created an unusual, although not unique, situation at this time, as the 1956 re-release was still in wide theatrical distribution throughout the entire year.