You could probably put it back together and run it.. being careful when putting the engine cover/air box back on.. but I think I would start looking for one. I trust you still have the clip at the very top of the maf housing that hooks back into the manifold? Once assembled it shouldn't go anywhere.. But pulling on the engine cover without regard to that missing might kick it loose..

Might want another pair of hands in there.. holding the maf housing steady while putting the cover on..