The following weapons were used in the film The Pest:
The first weapon seen in the film, the Beretta 92FS first appears in a hidden thigh holster on a member of the Scottish mob who confronts Pestario "Pest" Vargas (John Leguizamo) about a debt he owes them, as well as other members of the mob later on in the film, all the Scottish mobsters' Berettas have plaid-pattern grips on them. Another one can be seen among a collection of weapons later on in the film but turns into a flashbulb-firing non gun when Gustav Shank (Jeffrey Jones) fires on Vargas with it. It can also be seen in the hands of police officers who arrest Gustav at the end of the film.
When boarding a helicopter for Gustav's private island, Vargas' incessant hyperactivity aggravates Gustav to the point where he draws a Makarov PM to kill Vargas right then and there, but is stopped by his assistant Leo (Tom McCleister) before he can use the weapon.
After arriving at Gustav's private island, Vargas is told the real reason he was brought there; so that Gustav could hunt him. Initially mortified and paniced, the offer of $50,000 cash if he survives twenty-four hours changes his mind and he then takes an antique blunderbuss off the wall as he accepts the challenge.
While preparing for the hunt, Gustav can be seen loading a Luger P08. He draws it later on when he tracks Vargas to a nightclub, but doesn't get the chance to use it before Vargas escapes. Gustav's son Himmel Shank (Edoardo Ballerini) can also be seen with one when Vargas' family, girlfriend, and his girlfriend's family are being held hostage aboard the S.S. Lane Victory.
During preparations for the hunt, Gustav can be seen briefly handling a stainless steel Desert Eagle, though places it back on the table with the other weapons when Vargas arrives. Leo can be seen brandishing it later aboard the Lane victory when in a Mexican standoff with Vargas, though drops it when Pest fires a burst from an M16 he had procured earlier.
Freedom Arms "The Patriot" Mini Revolver
When Vargas arrives for the hunt, he objects to Gustav and his group being armed, to which Leo responds by presenting him with a Freedom Arms "The Patriot" Mini Revolver. Vargas then grabs the weapon and threatens to shoot the others before the hunt even begins, but has the weapon kicked out of his hands by Leo. He later draws and fires it when Gustav tracks Vargas to his girlfriend's house on the mainland, though fails to score any hits.
Remington Model 700
During the hunt, Himmel (Edoardo Ballerini) can be seen with a scoped Remington Model 700 and a bandolier of extra ammo, though he never uses the weapon as he's he only member of Gustav's group who objects to the hunt.
Another weapon carried by Himmel (Edoardo Ballerini) is an RPG-2 with a fake RPG-7-style PG-7V rocket that has an orange warhead with black stripes. Himmel accidentally fires this at Vargas and believes he had blown Vargas up, though it's later discovered that the rocket had missed him.
Winchester Model 70
During the portion of the hunt on the island, Gustav can be seen using a scoped Winchester Model 70, though never gets the chance to use the weapon on Vargas, instead firing it only to free Himmel from a trap Vargas had set for his pursuers.
Gustav can be seen brandishing a Kimel AP-9 aboard the Lane Victory, intimidating the hostages by pantomiming firing on them with it. He later has it when chasing Vargas below-deck, firing a burst in frustration. He then aims it at Vargas during the Mexican standoff, but drops it when Pest fires a burst from his M16 at him.
In some shots, Gustav's Kimel AP-9 switches to a rubber prop of an Intratec TEC-DC9, then back to the AP-9. The biggest distinguishing factor being the front sight design.
When Vargas and his friend Chubby (Aries Spears) arrive on the Lane Victory to rescue the hostages, the two make their way into the armory, Chubby grabbing a pair of M16A2 rifles from a crate. The rifles appear to be locked & loaded with full magazines in the crate, completely ignoring proper weapon storage guidelines.
When Vargas confronts Gustav and Leo, the M16A2 he procured earlier has changed into a slab-sided M16 rifle with A2-style handguards and A1-style lower receiver (evidenced by the magazine release fencing seen in the screenshot below) and birdcage flash suppressor. It also appears to have some kind of washer or bolt stuck to the side of the carry handle to imitate the M16A2's larger windage adjustment knob. When the villains refuse to release their hostages, Vargas fires a full-auto burst at them, causing them to drop their weapons.
Colt MK IV Series 70
At the end of the film, a police officer taking Gustav into custody can be seen armed with a holstered Colt MK IV Series 70 as his sidearm.
When Gustav is preparing for the hunt, he has an arsenal of weapons laid out on a table in the yard of his mansion. Among the weapons seen are a Beretta 92FS, Desert Eagle, Luger P08, RPG-2, Winchester Model 70, Remington Model 700 (with a bandolier of spare ammo), and an unknown M1911 variant with stainless steel finish, compensator, and wood grips.