My script recently made it to the top 10% of Nicholls and the Quarterfinalist round for Zoetrope and the Final Draft Big Break contest. Is that something worth including in queries? Or are agents/managers just going to see that and say to themselves, "He couldn't make it to semi-finalist?"
You're probably not far off with your latter assumption. As much of an achievement it is to be a Quarterfinalist, it's probably not quite impressive enough to pry open the door on its own. If you've got a kickass logline, though, that's a different story. But then, if you have a kick-ass logline, it'll probably stand on its own without the Quarterfinalist note.
Being in the top 10% of Nicholl entries is kind of the same thing. Last year there were 7,197 entries in the competition, which means that 10% of that places in you in the top 720 or so scripts. And since you didn't make the top 5%, it's safe to assume that there are at least 359 scripts that were better than yours.
When you break it down like that, it doesn't sound quite so good. As with everything, it's a judgement call. If it was me, I'd probably lead with the hook of the script rather than the achievements unless you've got some serious accolades.
Samuel asks a good question about plausibility:
I'm writing a script that relates to a couple trying to adopt a child from another country. One of the key plot turns in my script is when the couple discovers they don't fulfill a little known requirement that the foreign government holds for prospective adoptive parents. My problem is that when people read my script, they feel like this regulation is too far-fetched and that I bring it in only as a convenient plot device to serve my own purposes. However, the truth is that this particular foreign regulation is actually REAL and I'm not making it up. I have no idea on how to make that evident to the reader short of just telling him/her that when I give them the script to read. Is there any way to make it clear in a script that I'm not making something up?
Honestly, there isn't. And I advise against putting a note in the script because that still doesn't solve the problem you have of figuring out how to convince an audience that this is real.
My go-to example in these cases is usually Apollo 13. Almost every thing in that movie is accurate and there are some twists that would be called out if they sprang from the mind of a Hollywood writer. The two I'm thinking of in particular are when Mrs. Lovell loses her wedding ring in the shower and then later when the NASA scientists are tasked with figuring out how to essentially fit a square peg into a round hole using only the materials on the space craft.
That task in particular seems incredibly difficult and somehow the scientists pull it off within an extremely tight time limit. (There's even some drama when the astronauts make a mistake and tear a plastic bag that's essential to the procedure. Fortunately that problem is easily solved.)
On the other hand, I'm sure I've heard of cases where writers have taken the step of removing the most implausible details of "based-on-a-true story" adaptations because they know the audience will be pulled out of the narrative by them. In those cases, I'm pretty sure they were side details that were mostly unimportant to the larger story, so removing them wouldn't take the teeth out of the script.
But if your script hinges on this twist, you might have to just bite the bullet and go for it. There's also the possibility that something else in your script isn't working and your audience has one foot already out the door when this new twist arises. If you can reinforce the rest of the story, perhaps this one element won't be catastrophic.