Yeah, Ollie's survival (or, the lack of an explanation as to how) was pretty lame, even for a show like this. He was stabbed in a place - almost in the center of the gut - that should have punctured a major organ or two, not out further to the side or under the collarbone where TV heroes get shot or stabbed when they need to recover quickly with little or no damage. And falling all that way onto a rock outcropping should have resulted in some broken bones, at least.
They glossed over all that a little to cavalierly. If Ollie makes it back with basically no damage, it makes the whole fight with Ra's kind of pointless.