Planet Terror concept art by Alex Toader

a) Alex Toader did concept art for the Quentin Tarentino produced movie directed by Robert Rodriguez Planet Terror released in April in 2007.

b) The image featured below features a vaguely Alien inspired creature which has spine like limbs coming out of its back and it one takes a look at the concept work for Alien vs Predator Requiem, one can find similar sorts of limbs protruding from the backs of Predaliens in the concept art. And is so happens that Spiderman appeared as Iron Spider was introduced to the comic book world in July 2006 in Civil War Vol 1 in which he wears an armoured outfit featuring similar back limbs.

woman about to lose her leg to a alien mutant who is about to cut it off

The alien/mutant pictured here has an elongated head with a long ribbed throat that could be seen as something very definitely inspired by the Alien design. 

Alex was asked by Robert Rodriguez to draw aliens, before he changed it to mutant monstrosities, however the director settled for classic zombies instead in the end.

1. Alex Toader:(GrindHouse)...originally Robert wanted the creatures to be aliens ...then mutant zombie monstrosities...but towards the beginning of the shoot, he settled for just good ole' classic looking zombies (source art-of-alextoader.blogspot.co.uk, February 2008)

heroine pulling the snake tongue of the mutant alien

The main character in this movie is a woman who loses a leg and it is soon replaced with a machine gun. Around at the same year of the release of this movie, another film, a Japanese movie The Machine girl was released where the main heroine loses a limb and it's replaced by a machine gun.  (released May, 2008)

heroine firing machine gun into the air