When I render, only some emissions and some gloss render, while others doesn't I've worked in blender for a bit over 2 years now, and I've never encountered something like this before. I was modeling a stage (for performances, etc) and when I tried to render, some of the emissions wouldn't render at ALL. Some would, which is very weird. I'd be really grateful if anyone knew what I could do, because I'm completely lost... :/

.blend :
I think I found your problem. 

You had certain objects set to NOT render by turning off the camera icon.
Just turn them all back on and it should render fine.