The following weapons were used in the film Runaway:
Dr. Charles Luther's "smart" missile gun
The missile-firing pistol used by Dr. Charles Luther (Gene Simmons) in the movie was probably designed by the prop department. Though the model info is unknown, the base of the gun is clearly a 1911 style frame, probably provided by Detonics. Interestingly, the publicity materials for the film (especially in the theatrical poster) showed Tom Selleck holding the gun though he never uses it in the movie. The story alludes to one of the scientists working with Luther being an expert in propulsion & perhaps the supplier of the gun & its ammo. The runaway squad's chief tech officer (Stan Shaw) later calls the mini-rockets "smart bullets."
The projectiles are all electronic "heat seeking missiles" with a back half made up of solid propellant, making use of valves for directional control. They are able to be programmed to "go after" a specific person using a person's unique heat pattern as a signature.
The missiles, while in flight, are depicted as nothing more than black streaks. This was quite effective in real time as the film was made long before freeze framing on computers was possible. But here, it shows us they may have simply painted on the film negative to animate the bullets.
Detonics 1911 Custom
The Detonics ServiceMaster is used as the service handgun of Sgt. Jack R. Ramsay (Tom Selleck) and Officer Karen Thompson (Cynthia Rhodes). The gun has the characteristic Detonics forward mounted rear sight, which was featured on the Combatmaster, but the longer grip frame of a Servicemaster. It should also be noted that there is a line present on the slide where a combat master slide would end, the same gun can be seen in Terminator 2: Judgment Day used by Linda Hamilton.
In the third act of the film, while trying to protect Jackie Rogers from Luther both officers use compact Detonics Combatmasters as sidearms.
Unknown snub revolver
This is likely to be a Smith & Wesson chief's special, but it is never shown well enough to be sure. Johnson uses it to fire at Ramsay after he kicks in the hotel room door, thinking it's Luther come to kill him.
Smith & Wesson Model 19
The 2.5"-barrel Smith & Wesson Model 19 is used by a robot (!)
In one of the films more tense scenes, Ramsay uses a laser gun with a battery pack on his belt to stop a murderous runaway inside a suburban home. It should be noted that Tom Selleck's character only fires this weapon in the film. He never fires his main sidearm, or his compact backup.
Custom Police Belt
Today it is very common to see officers carrying semi-automatic handguns, but in 1983 (when the film was shot) most police agencies issued revolvers. These custom belt rigs were way ahead of their time.