Starting with the sculpt, it just looks... ugh.
It's like every part of his face is immovable save for the Elvis curl. Only the left half of Stallone's face has nerve damage, so potentially putting a bit more emotion/expression in the right side, and bringing down the irises of the eyes to remove the pothead stare, might help. Next up, the Donnie Osmond poof needs to go. The hair should be flatter and sweaty, not fluffed like he's ready for his Barbazon headshots. By this scene in the movie, he's drenched in sweat and it's clearly the shot they're going for. For the body, the pose would be great for a First Blood PF. But for Part II, no. The left arm is curled too high and he's not tucking the MK43 in enough on the right. I don't know how you'd fix that being that the gun and body are likely separate pieces. Maybe curl the shoulder in more? Other than that, putting him in a slightly deeper squat would sell the stance better.