Whilst the God Anubis attended the Weighing Of The Heart during Judgement, Anubis never ate the hearts/souls of the damned, the hearts of the damned were devoured by Egyptian demon Amiit "The Devourer Of Hearts".
Corporal Shadid fires his rifle down the crawlway at whatever has been following the group. But, firing a rifle in a confined space which the group was in would have been incredibly deafening and their hearing would have been affected, even if temporarily. In addition, there were no spent casings being seen or heard ejected from his rifle as he fired.