You've got a stray orange pixel on the right side.
The shadows on the faces (Robocop and horn-helmet person) don't read at all at 1x, I think they're redundant. If you darken them enough for them to make a difference, I think they'll still not really look like shadows, so you might as well get rid of them. The shadows on the skeleton, on the other hand, could also stand to be a little darker.
Shadow issues aside, these overall read very well, and I recognized a few of these characters right away (the rest, I just don't know).
cheers, i wasnt really drawing anything in particular and just decided on deadpool and robocop at the end the rest are just OC