The 12-wheeled "Landmaster" vehicle used in the film was created by Jefferies Automotive in Universal City, California. Despite the appearance of two "Landmasters" in the film, only one was built at a cost of $300,000 in 1976. The Landmaster is powered by a 391 cubic-inch Ford industrial engine, and features a fully-functional, custom-built "tristar" wheel arrangement, which could actually help it "crawl" over boulders. It also used an innovative steering mechanism that guided the vehicle, not by the front wheels, but by "bending" the middle section with hydraulic rams to effect a turn. The Landmaster's bodywork was made with 3/8-inch steel plating, which helped it tip the scales at over 10 tons. It was so tough, in fact, that it survived a 25-foot jump during testing with no damage. As of today, the original "Landmaster" is alive and well, and is currently in the hands of a private collector who purchased it in 2005. It has been restored to its original condition as seen in the film.
The movie sat on the shelf at 20th Century Fox for some time after production was completed in 1976. Fox had high hopes for it on its release in 1977, expecting it to do better at the box office in comparison to Fox' other sci-fi release scheduled for that year... Star Wars: Episode IV - A New Hope (1977)
Damnation Alley was 20th Century-Fox's big-budget science fiction project in 1976 while Star Wars: Episode IV - A New Hope (1977) was a little-publicized modest film in production for the studio at the same time.
The infamous armor-plated "killer cockroaches" are in fact Madagascar "hissing" cockroaches. In reality, they are three-inches long (as seen in the film), and are quite benign. They make the "hissing" sound to communicate with one another, and when they are agitated. Live roaches were used in close up shots, but rubber mock ups were used in the wide and group shots.
20th Century-Fox "developed" a rival to Universal's gimmicky "Sensurround" sound process (popularized in the theatrical release of Earthquake (1974)) that was only used for the theatrical release of "Damnation Alley" called "Sound 360." This process was basically a variation of Magnetic-Optical Stereo sound. This technical advancement/gimmick in sound did not last past "Damnation Alley" although it was planned for Walter Hill's The Driver (1978) and Damien: Omen II (1978). If you look at the one sheet of "Damnation Alley" the "Sound 360" declaration and logo are prominent at the bottom.
The bizarre, colorful patterns in the sky seen during the post-war scenes were accomplished by filming lasers hitting various types of material, and using the blue sky in the live-action footage as a "key" to insert the resulting patterns. This time-consuming process is what kept the film in post-production longer than expected