In Season 1 (or "Day 1"), CTU Agent Jack Bauer must stop a plot to assassinate presidential candidate David Palmer while his wife Teri frantically tries to discover the whereabouts of their daughter.
The following weapons were used in Season 1 of 24:
Agent Jack Bauer (Kiefer Sutherland) of the Counter Terrorism Unit (CTU) in Los Angeles carries the SIG-Sauer P228 with a nickel-plated slide as his weapon of choice throughout the day. An interesting and well-known goof is that in several scenes, the gun changes from the SIG-Sauer P228 to a SIG-Sauer P229.
SIG-Sauer P226
In Episode 13 - "12:00P.M. - 1:00P.M.", a SIG-Sauer P226 is pulled by Kevin Carrol (Richard Burgi) when he realizes that there is a trap.
Smith & Wesson SW99
Andre Drazen (Željko Ivanek) is seen carrying a Smith & Wesson SW99 as his sidearm of choice, notably during the prison raid to free his father Victor as well as on the docks in Episodes 23 and 24. The handgun also used by one of his henchmen.
Beretta 92FS
CTU Director Richard Walsh (Michael O'Neill) uses a sound suppressed Beretta 92FS when he is taking fire from Ira Gaines' well-trained assassins during Episode 2 - "1:00A.M. - 2:00A.M.". This gun is also used by operatives employed by Ira Gaines (Michael Massee) as they are seen about to execute the Bauer family during Episode 8 - "7:00A.M. - 8:00A.M." and the shootout with Jack. Berettas are also the sidearms carried by uniformed LAPD officers. Ira Gaines is also seen using Beretta when confronting Dan and when he was wounded by Jack. A Beretta is also the weapon taken by Teri Bauer (Leslie Hope).
Alexis Drazen (Misha Collins) uses his Glock 19 9mm to tie up loose ends during Episode 14 - "1:00P.M. - 2:00P.M." A suppressed Glock is also used in CTU during Episode 24 - "11:00P.M. - 12:00A.M."
Glock 17
CTU Agent Ted Paulson (Kevin Ramsey) draws his Glock 17 after realizing there's a security breach at the safe house during during Episode "3:00P.M. - 4:00P.M." The assassin Jovan Myovic's USP switches into one of these when he's hiding behind a tree on the Bauer property. Jack also steals one from a Secret Service agent and later uses it during the rescue of his family.
Heckler & Koch USP
Jack Bauer (Kiefer Sutherland) takes two Heckler & Koch USP pistols into the climactic gunfight with the Drazens during Episode 24 - "11:00P.M. - 12:00A.M." and dual-wields them for the majority of the shootout with Andre Drazen (Željko Ivanek). After being wounded by Viktor Drazen (Dennis Hopper), Jack Bauer is seen using his one remaining USP, emptying the magazine. A common mistake is that when his is empty the slide stays locked in place and it clicks each time he pulls the trigger. A suppressed Heckler & Koch USP was used by Jovan Myovic, an assassin working for the Drazens. USP's are also used by Ira Gaines' well-trained assassins during Episode 2 - "1:00A.M. - 2:00A.M.", where one is seen on the ground when Jack cuts the thumb off one of the assassins he killed.
Jericho 941
A Jericho 941 is used by CTU Agent Tony Almeida (Carlos Bernard), but later it appears to switch into a Beretta or Taurus type pistol.
The undercover cop Krugman pulls a Smith & Wesson 5906 during the drug deal with Frank Allard in Episode 19 - "7:00P.M. - 8:00P.M.".
Smith & Wesson 5904
The Smith & Wesson 5904 is Dan's weapon which Rick later gives to Teri Bauer, but it malfunctions when Teri tries to use it.
Taurus PT92
Tony Almeida (Carlos Bernard) uses (in most likely a continuity error) a Taurus PT92 when rescuing Teri in Episode 19 - "6:00P.M. to 7:00P.M.".
Walther PPK
A Walther PPK is used by the female undercover cop doing the deal with Frank Allard in Episode 19 - "6:00P.m. - 7:00P.M.".
Submachine Guns
Cobray M11/9
A Cobray M11/9 is used by Ira Gaines's henchmen, most notably Kevin Carrol during the shootout with Jack.
Micro Uzi
The IMI Micro Uzi is used by one of the guys helping Frank rip off the dealers, and some of Ira Gaines' other men during the shootout with Jack. Oddly, the Micro Uzi appears to be on the table Dan's corpse was placed on, despite that his weapon was the Smith & Wesson 5904.
IMI Uzi
Rick Allen (Daniel Bess) grabs an IMI Uzi during the rescue of Jack Bauer's family during Episode 12 - "11:00A.M. - 12:00P.M." Jack (Kiefer Sutherland) also uses an IMI Uzi to set off a car explosion during 11:00A.M. - 12:00P.M. This SMG is also used by Andre Drazen's men in Episode 21.
Heckler & Koch MP5A2
CTU tactical teams are carrying Heckler & Koch MP5A2 submachine guns during the rescue of Jack Bauer's (Kiefer Sutherland) family during 12:00P.M. - 1:00P.M.
SA Vz.61 Skorpion
SA Vz.61 Skorpion machine pistols are used by at least one of Drazen's henchmen in final gunfight.
Shotguns
Mossberg 590 Cruiser
A short barrel variant of the Mossberg 590 is pulled from a bag by Frank Allard (Edoardo Ballerini) in Episode 19 "7:00P.M. - 8:00P.M."
Remington 870
A Remington 870 is seen in the police car in Episode 4 "3:00A.M. - 4:00P.M."
Rifles
Remington 700 AICS
The assassin Jonathon Matijevich (Rudolf Martin) takes target practice using a modified suppressed Remington 700PSS on a (Accuracy International Chassis System) AICS platform.
M16A1
An M16A1 rifle is carried by at least one of Ira Gaines' henchmen, with A2 Variant style handguards during the scenes when Andre Drazen arrives at the compound and the shootout with Jack.
Norinco Type 56
A Chinese made Norinco Type 56 is seen slung over the shoulder of one of Ira Gaines's henchmen before the shootout with Jack in Episode 12 - "11:00A.M. - 12:00P.M.". One of Andre Drazen's men carries a Norinco in Episode 21 "9:00P.M.-10:00P.M."
AKM
AKM rifles are used by Ira Gaines's men during the shootout with Jack and Andre Drazen's men during the assault on the DOD Class 3 Detention Facility and at the docks.
Norinco NDM-86 (chambered in .308)
Ira Gaines (Michael Massee) hunts Jack Bauer (Kiefer Sutherland) through the woods at the compound with a Norinco NDM-86 chambered for .308. The Norinco NDM-86 is a Chinese-made clone of the Soviet SVD. The squared off shape of the box magazine shows the chambering as being in .308 rather than the curved magazine for the rifle's original 7.62x54R cartridge.
AR-15 variant
Agent Teddy Hanlin (Kirk Baltz) shoots a suspect with some form of suppressed AR-15 variant. A possibility is the Panther Bull Sweet Sixteen.
XM177 Mock-ups
What appears to be some type of M16A2 carbine variant (probably the Model 725) with chopped barrels, weaponlights and fake XM177-style flash suppressors installed is used by Jack Bauer, Warden Mark DeSalvo (Lou Diamond Phillips), and some untrained civilians during the raid on the DOD Class 3 Detention Facility in Episode 20 "7:00P.M.-8:00P.M." and Episode 21 "8:00 PM - 9:00 PM"
Other
Heckler & Koch P2A1 Flare Pistol
In Episode 19 - "6:00P.M. to 7:00P.M.", a modified Heckler & Koch P2A1 Flare Pistol is used by Jovan Myovic (Henri Lubatti) to fire a miniature spear.
Ira Gaines' Table of Weapons
In Episode 3 - "2:00 AM to 3:00 AM" at the compound, a number of unknown weapons are seen on Ira Gaines' table.