The backgrounds definitely look faked to me. Looks like you selected them as best you could and applied some sort of 'bokeh/blur' effect.
I read the jeep as part of the scene, I dunno why it's following the dude, but it looks like it is.
The gas mask is a bit trite. For some reason people cannot stop putting gas masks on models.
Do I like 'em? Well, they're heavily stylized. It's not a style I love, but I think it's consistent-ish. The background effect is too evenly applied, same for near as for far, which makes it look a bit comic-booky, but maybe that's part of the style, I dunno. Regardless, I feel like the edge between the dude and the background needs to be feathered a little better so he doesn't look quite so pasted-in.