The film was allowed to shoot at a real California mall as long as they did not damage any facilities and had removed any traces of their presence before the mall opening time of 9AM. While the mall's head of security didn't like the filmmakers and was constantly accusing them of causing disrepair, the mall's owner was supportive of the film and made sure the production was able to complete its work on schedule.
The budget for the film was very limited (around $800,000 total) but the director had no problems with this, as he was happy to work on a Roger Corman film and knew beforehand that Corman always kept expenses to a minimum.
The movie was originally theatrically released in March 1986 under its original title, "Killbots." It performed poorly during its initial release. The producers felt the movie's title might have disinterested audiences, who might think based on the original movie poster that it was a "Transformers"-like children's cartoon instead of a violent exploitation movie. After some time, the movie was re-released on video under its new title with over 15 minutes cut.
The special effects crew actually built five remote controlled robots to serve as the Protector killbots. Three were required for the scenes of the robots together in the first half of the film, with two extras as backups in the event that the originals were damaged during any of the action sequences. In order to keep the robots looking realistic (as well as due to the film's budgetary constraints), they were constructed out of such items as wheelchair frames and pieces of conveyor belt. Excluding shooting laser beams, most of what the killbots are seen doing onscreen was the result of the effects crew operating them via remote control.
Filmed in Sherman Oaks Galleria, the same mall used in Commando (1985). Most notably when near the elevators. Both films would've been filmed around the same time. But due to budget constraints, Chopping Mall (1986) was filmed after close of business.
The inciting moment that kicks off the action is identical to "Short Circuit". Robot gets struck by lightning. However, the results are exactly opposite. In short circuit a killer military robot becomes a sweetheart, whereas in "Chopping Mall" good security robots become killers.
The trivia items below may give away important plot points.
When the stunt crew was setting up a scene involving a character being thrown to his death from the third level of the mall, director Jim Wynorski volunteered to try the stunt himself as long as they set him up from the second level. He completed it successfully but found out he'd broken a rib in the process; Wynorski did not tell anyone he had gotten hurt and no one found about it during the remaining production time.
Despite the iconic VHS cover and ad campaign, the mechanical claw seen gripping the bloody shopping bag never appears in the film. Similarly, there is only one actual mutilation in the film (the exploding head scene). The rest of the victims die either by having their throats slit, being electrocuted, set on fire, or falling to their deaths.