This and the three other films in the same package were originally supposed to be shot in Mexico City, but since Boris Karloff was suffering from pneumonia and had only one lung (the other had developed cancer and been removed), his doctors told him not to travel to Mexico City because of the thin air at its high altitude. So Karloff's scenes were shot in Hollywood instead.

This film was shown in the USA in Spanish language theaters before being dubbed in English and sold to television.

This was one of a group of films made primarily in Mexico with all of Boris Karloff's scenes being shot on a soundstage in Hollywood. This would be Karloff's next to last feature.

One of a package of four films Boris Karloff made as co-productions between Columbia Pictures and Mexico's Azteca Films, though after Karloff's death Columbia sold off their share to a distributor called Horror International.

A poster of this film is on display in the new "Ghostbusters" (2016) movie, when the villain recreates the glory days of 1970s New York City, complete with movie posters ("Taxi Driver" is also included), neon signs, naughty businesses, billboards advertising products from the time period and even an sign celebrating the end of the Vietnam War.

During filming, Karloff was approached by fans to record a sample of his voice onto their small tape recorders.