In the third-tier 'dream world' the Wiseman (Scott Glenn) presents Baby Doll with her weapons, one of which is a nickel plated engraved M1911A1 pistol with spare magazines (and small jewelry attachments). In the real world, a blued M1911A1 is the primary weapon of Baby Doll (Emily Browning).
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.
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.
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 SureShot reflex sight.
An M4A1 with rails and a SureShot reflex sight is used by Sweetpea (Abbie Cornish), apparently fitted with a suppressor during the hunt for the dragon.
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.
Blondie (Vanessa Hudgens) use a Daewoo K3 light machine gun fitted with a rail forearm and vertical grip (standing in for the FN Minimi SPW). It is recognizable as a K3 due to the shape of the gas tube and front site, visible in the second screencap below.
The Wiseman (Scott Glenn) uses an anachronistic 03A4 Sniper rifle in the trenches of World War 1, when he explains how the Germans are reanimating their dead with clockwork mechanisms and steam.
A Browning M1919A4 is seen being chambered by Blondie (Vanessa Hudgens) in the air battle with the dragon before the dragon swallows the tail section of the plane.
