Arachnid is a 2001 English language production from producer Brian Yuzna (famous for such horror movies as Necronomicon and The Re-Animator film series). Since Yuzna is based out of Spain, most of his production is Spanish including many of his stars, however he does use American or British actors to secure international distribution. Arachnid is an average "B" Monster Movie, however, upon closer inspection, it has one of the most rapid breaks in gun continuity this side of an Uwe Boll Movie as characters are given one firearm at the beginning of the film and end up with another gun at the end.
The following weapons were used in the film Arachnid:
Lauren's brother, Pilot Joey Mercer (Jesús Cabrero) aka Call Sign "Lightfoot" aims his Colt M1911A1 at a creature. Though he is wearing some strange looking Air Force insignia, in the story he is supposed to be a "Navy flier" who is piloting an F-117 Stealth plane when he crashes. I guess the screenwriter didn't know that the US Navy doesn't fly F-117 Stealth fighters, and the actor is wearing Air Force Style insignia.
Colt MK IV Series 70
Reyes (Luis Lorenzo Crespo) carries a bright blued Colt Series 70 M1911 pistol. Valentine carries a Series 70 M1911 as well but his pistol has offwhite stag horn grips.
Star Model Super
Bear (Watts Rockeford Allen) also has his own M1911 style pistol, but he uses a Star Model Super (chambered for the 9mm Largo round). The Star Model pistol is identifiable by the external extractor and the slightly longer slide (than the Model A or B).
Susana (Neus Asensi) carries and fires a Browning Hi Power pistol (or clone).
* Looks like a Browning BDA
Valentine (Chris Potter) is given a bright blued Ingram MAC-10 with a barrel extender at the beginning of the film. Using the barrel extender is recommended being that the MAC-10 has a high rate of fire and the extender allows the shooter to use both hands. Unfortunately Valentine rarely uses both hands to fire....
Towards the end of the movie, Valentine's Ingram MAC-10 mysteriously changes into an Uzi 9mm Submachine Gun!
Colt AR-15 SP1 Carbine
In the beginning of the film Reyes (Luis Lorenzo Crespo) and Bear (Watts Rockeford Allen) are issued Colt SP1 Carbines with 16" barrels, however they change to 14.5" Colt Model 654 Carbines (the export model of the 653 with slab side receiver) constantly between shots. Both the 16" and the 14.5" versions are seen firing fully automatic in the film. This is the least obvious continuity error in this film. The SP1 Carbine is also used by Lauren Mercer (Alex Reid) throughout the rest of the film. The Colt Carbine that Lauren Mercer (Alex Reid) uses changes many times during the film, something which the actress seems to be acknowledging in the film. When the gun changes, the actress seems to look at the gun with perplexed look on her face, seemingly a nod to the fact that the armorer had a completely different gun for that shooting day.
Colt Model 654 Carbine
Using an armorer from Spain, the production apparently had access to the Colt model 654, the export model of the 653, which unlike the 653 has the slab side like the SP1 receiver. It appears upon close examination that these rifles have 14.5" barrels rather than the full sized 16" ones from the SP1 Carbine.
Colt Model 765 Carbine
Lauren Mercer's gun changes again from a slab side SP1 to a carbine with an A2 rear sight, forward assist and brass deflector. The 765 Carbine is the closest candidate.
Mercer's gun changes yet again to a Colt M16A1 with A2 handguards.
Colt Model 733
Lauren Mercer's weapons changes yet again to a Colt Model 733 Carbine with a 11.5" barrel and A1 Style birdcage Flash hider.
Is it my imagination? or is the barrel slightly shorter in these shots? Thus indicating yet another weapon? Based on the off color of the barrel, it seems to be a commercial barrel cut down to resemble a Colt 733.
Colt 733 Carbine with A2 Flash hider
Later in the film Mercer's 733 has an A2 flash hider instead of the previous A1 Birdcage.
Colt 733 Carbine with original M16 3 prong flash hider
Later in the film Mercer's 733 has the original three prong flash hider.
Colt 733 Carbine with no flash hider
When Valentine fires the same gun, it has no flash hider at all.
Goofy firing stances
In this film, no one (except the pistol shooters) seems to aim at all. Everyone with a submachine gun or assault rifle fires 'underhand' like a softball pitcher and most of the time their guns are cock-eyed to one side. It was consistent throughout the film so it was a conscious directorial decision.