Actually, it's more than that. The entire arm assembly should be sitting much further back. You slide both arms all the way back, then if you slide them forward just a tiny bit, there's a third spot for them to fit into (it has a soft-lock - you should feel it if you do it right), make sure the green panels are flipped out from inside the shoulder panels, then tab it all in down the sides. Don't forget to flip the green chest tab up. Also, the gun can tab onto the side of the helicopter mode. And that's pretty much that. The arms only sit forward in vehicle mode. If in doubt, go through the official pictures here and on their Weibo page, and you'll figure it out soon enough. I'm still not sure what those little thruster pieces on the backs of his legs open up for though. They only move between robot mode and either vehicle mode, but they're not meant to open up at any stage that I can see, so why they're engineered as a bunch of separate pieces is beyond me. Agreed, it feels off, though the hands seem like they're sculpted to be 5mm-compatible, and the gun fits nicely into mine (but obviously still wobbles from side-to-side). The sword... not so much. I really wish they had come up with a nice, creative tabbing system. That would have made a huge difference. FYI, you can get him to hold the bomb pretty easily with a splayed-open hand. If you can't get it to sit, fiddle with it for a bit. I didn't really have any trouble getting it to work but I've seen at least one other person mention he couldn't hold it (but he can). It doesn't fit nicely into his hand or anything though. It just balances there (pretty well, if you ask me).