The only efficient sights for such a weapon would be a Red Dot Sight or an open-eye no magnification sight. If even a 4X Tijicon ACOG was on there it would be WAY overkill.
No silencer, and no, not the MP5K although one guy had one of those. It was not a red dot, I know that for sure, it was longer and more like some sniper rifle sight. In reality it was probably some shitty prop for the film that isn't real at all, just to make them look like they know what they're doing.