With a show like MythBusters, where there are specials that are not part of the regular episode #s, what is the best way to name them so Plex will order and name them in order of the air date (according to Wikipedia)?
Example:
In season 3 it goes “Episode 10: Bulletproof Water”, “The Jaws Special”, and “Episode 11:Border Slingshot”. According to original air date. according to thetvdb.com the episodes go S3E16-Bulletproof Water, S3E17-Jaws Special, S3E18-Border Slingshot.
I would like Plex to list episode 10, the special, then episode 11 in that order. And hopefully it will pull in all the correct meta data with little to no editing on my end. It doesn’t have to be correct in file explorer, but i would like it correct in Plex.
I know this is a very specific request, I just want to know if it is possible and if so, how to do it.
Your two options are Aired Order and DVD Order - the latter only available in Plex after the installation of the DVDOrderAgent Plugin.
Also, according to TVDB - where it really matters - the episodes you site are:
http://thetvdb.com/?tab=season&seriesid=73388&seasonid=637747&lid=7
A TV Show Library/
…MythBusters/
…Season 2005/
…MythBusters - S2005E16 - Bulletproof Water.XXX
…MythBusters - S2005E17 - MythBusters Jaws Special.XXX
…MythBusters - S2005E18 - Border Slingshot.XXX
DVDOrderAgent will be of no help at all because the DVD order listed at TVDB is completely out of whack according to what you have stated above.
Yes, you could get them to display in the order you want - after tedious misnaming and more tedious hand editing and it’s likely the first time Plex rescans the series all your hard work will go up in a mushroom cloud.
In the end it’s just easier to let FileBot (link in my signature) pre-match and re-name your episodes and let 'em play as they’re listed at TVDB.
or
Stick 'em all in a Home Video Library and Plex won’t try to match 'em at all, you can hand edit everything, gather and name poster images, etc, etc, etc.
There is also another (poor) option: Use TMDB instead of TVDB as the agent for your TV Show Library. Good luck with that, but if you go to: https://www.themoviedb.org/ and look up Mythbusters you’ll see several variations. The flavor I chose let me find some of your episodes in Season 3, but I’m not sure I have found Jaws among them and it’s sure not in Season 3.
Best to stick with TVDB I think.
Plex and TVDB have a very small window you can try to throw TV stuff through. It’s actually a teenie window in the exact shape of whatever it is you’re trying to throw through it. Capitulate or prepare for life-long battle with Plex - that will end with you dead and Plex the victor.
Plex doesn’t care about your personal pain and suffering or the lives of those you recruit into battle. It mindlessly grinds them under her heel and moves on to the next contestant.

I guess I will have to think about what is more important, the file name or Plex order. Is there a Wikipedia add on that you or anyone is aware of?
Not that I am aware of.
TVDB does contain the actual ‘air date’ and from my experience it’s accurate. Unfortunately some times, like in the case of FireFly, that actual ‘air date’ completely screwed up the show to the point that some argue the Network Executives killed it. In that case the DVDOrderAgent is your best friend as you can watch the episodes in the order the creator intended.