Yep, looks like you're missing the wire detent. Also the LP hose running from the LPR in the back to the MAC valve in the front. I'm pretty sure standard LP cocker hose would work (I've used it for the ram/MAC valve lines...), but I'm not 100% on that.
Other than that, it's pretty complete. Can't quite tell if there's a trigger switch on the wiring harness or not... If not and it's not in the trig frame then you can pick one up from a Radio Shack for dirt cheap.