A 26 Oct 1967 LAT item announced that American actors Gary Lockwood, Jack Palance, and Lee J. Cobb had recently filmed They Came to Rob Las Vegas in Madrid, Spain. According to the 8 May 1968 and 11 Sep 1968 issues of Var, the project marked a co-production between Spain, France, Italy, West Germany, Argentina, and the U.S. A significant portion of principal photography took place in the deserts of Almería, Spain, which stood in for the American southwest. Location shooting was done in Las Vegas, NV, San Francisco, CA, and Los Angeles, CA, where one sequence was shot at the Angels Flight funicular railway in the Bunker Hill area of downtown.
       Warner Bros.-Seven Arts, Inc. briefly changed the title to Our Man from Las Vegas, as noted in the 22 Mar 1968 DV. Five days later, however, a 27 Mar 1968 DV brief announced the title had reverted back to They Came to Rob Las Vegas. Previously, the 8 Nov 1967 Var had referred to it as Las Vegas 500 Million, and noted that filming had not yet been completed. Months later, the 13 Mar 1968 Var claimed that director Antonio Isasi Isasmendi was currently overseeing the editing. According to the 15 Jan 1969 Var review, the picture took “seemingly endless months of shooting, editing and looping” to complete.
       A tentative New York City release date was scheduled for 30 Oct 1968, as reported in the 11 Sep 1968 Var. However, the film did not open in New York until 5 Feb 1969. In the meantime, a 124-minute version debuted under the title Las Vegas 500 Milliones in Oct 1968 in Madrid. European releases followed in Jan 1969 in Paris, where a 120-minute version played as Les hommes de Las Végas; in Mar 1969 in West Germany, where a 130-minute version was titled An einem Freitag in Las Vegas; and in Italy, where the film was released as Radiografia d'un colpo d'oro. Despite receiving generally negative reviews in the U.S., it went on to become “successful on an international scale,” the 8 Sep 1976 Var reported.