First on the list: the Panzergrenadier StG. The Panzergrenadier StG uses the CoH1 model and texture, but some time in recent months, the texture sheet has been fucked up. This is what it looks like, compared to the Sturmpioneer StG (new texture, new model), and the original texture.
Next up, the Ostheer LMG 42 has a cloned receiver in the middle of the gun for no reason, and the magazine is attached to that instead of properly on the real receiver, and there is also a floating bipod off the end of the gun. The bipod and magazine seem to be parented (or attached to, a part of, etc) the second receiver, because if it were in the place of the first receiver, both these items would be in their rightful place as well.
Lastly, in many buildings, the infantry float above the ground and way above the window. In fact I think it's more common than not to see them float over the window, and it has been since CoH2's release. I do not remember this existing in CoH1. Not a major issue, but still a small bug.
(sorry for the cluttered image)