The Satan Bug is a 1965 thriller movie directed by John Sturges and loosely based on the 1962 novel by Alistair MacLean. A deadly virus nicknamed "The Satan Bug" is stolen from a top-secret bioweapons laboratory. Lee Barrett (George Maharis), a former intelligence agent turned a private investigator, is brought back to service to ivestigate the case and prevent the usage of the virus that can lead to the death of all life on Earth.
Colt Detective Special revolvers are used by Lee Barrett (George Maharis), the head of SDI (a fictional special service) Eric Cavanaugh (Richard Bull) and his subordinates, Ainsley's henchman Veretti (Edward Asner) and the pilot (Michael Barrier) of Ainsley's helicopter.
Smith & Wesson Model 36
When Veretti (Edward Asner) holds at gunpoint Barrett and Ann Williams in the minivan, his revolver switches to a Smith & Wesson Model 36 due to a continuity error. SDI agents, as well as one of the Ainsley's henchman, posing as an SDI agent, also use S&W 36 revolvers. Lee Barrett (George Maharis) seizes the revolver of the said fake agent in the climactic scene.
Smith & Wesson Model 10
Security guards of the Station Three lab and police officers carry revolvers in holsters. Smith & Wesson Model 10 seems to be a decent guess.
Pistols
Custom Luger P08
Ainsley's henchman Donald (Frank Sutton) is armed with a Luger P08, fitted with a perforated barrel shroud. The pistol was dressed as a futuristic weapon for the 1963 episode "Death Ship" (S04E06) of The Twilight Zone TV series and reused in Satan Bug (maybe this prop found usage in even more productions). When the pistol fires, there is only a faint smoke from the barrel, but the jointed arm moves, so this is not a toy gun. In one scene captured Lee Barrett (George Maharis) makes an attempt to escape, disarms Donald and seizes the pistol (it is seen very blurry in his hands) but in turn he is disarmed by Veretti (Edward Asner).
Shotguns
Remington Model 870
Two SDI agents who try to intercept the minivan of Ainsley's henchmen are armed with Remington Model 870 shotguns. During the confrontation they have to surrender the guns, and Donald (Frank Sutton) takes a shotgun. Remington 870 shotguns are also used by SDI agents and police officers in other scenes.