Revealed is a nickel plated engraved M1911A1 pistol with spare magazines. A Nickel M1911A1 is the primary weapon of Baby Doll (Emily Browning).
Flintlock Pistol
During the trench battle with the World War One German Zombie Soldiers, Rocket (Jena Malone) uses a combination of bayonet and single shot flintlock pistol. She uses the pistol as a club in hand to hand combat, which is probably the most practical use for the antiquated weapon in that battle. Actually as far as i know flintlock pistols are intentionally heavier so they could be used as a club.
Remington 870
In the battle with armed automatons, Sweetpea (Abbie Cornish) uses a tactical Remington 870 Shotgun with surefire light, door breaching muzzle, and Blackhawk M4 style stock.
Heckler & Koch MP7A1
Baby Doll (Emily Browning) appears to use a suppressed Heckler & Koch MP7A1 with a vertical foregrip. Refreshingly as far as the trailers show all the girls actually manage to use the vertical foregrips on their guns as opposed to many people who ignore them or use them inconsistently.
During the air battle and the sweep into the Dragon's lair, Rocket (Jena Malone) carries Heckler & Koch UMP-45 with foregrip and C-More sight.
M4A1
An M4A1 with rails and a C-More Sight is used by Sweetpea (Abbie Cornish), sometimes outfitted with a suppressor.
Single Action Army
Looks more like a Colt 1860 Army with a Richards conversion. Note the rear sight on the frame ring, not the hammer. - Gunmaster45
Lewis Gun
Unidentified Carbine
In what may seem like an anachronism, in a film filled with (intentional) weapon anachronisms, a zombie German World War One Soldier attacks Blondie (Vanessa Hudgens) in the trench with a rifle that has its bayonet mounted. German soldiers from WW1 would be issued the Mauser Gewehr 1898 rifle, but this is far too short to be even the anachronistic Karabiner 98k.
Modified M61 Vulcan
Unidentified Auto Cannon
On the left arm of the "Bunny Rabbit" 'Gundam' as it shoots down an attacking Bi-plane.
TBD Weapons
In the battle with the robots, we see heavily modified weapons which look like they may be based on real world guns.
M249 Para Model
What looks to be a paratrooper length M249 with rails is seen being held by Blondie (Vanessa Hudgens).
Short Magazine Lee-Enfield (SMLE)
As the girls walk past the British Soldiers during World War One, the British Soldiers are carrying SMLE No1. Mk III rifles - .303R