From looking at the following link, it looks like Tygra used a handheld communicator in ‘Mongor’.
http://maruschak.wordpress.com/2009/02/10/review-thundercats-season-1-episode-19-mongor/
There it states Panthro developed the communicators in their weapons during ‘The Time Capsule’.
Indeed. I think this is an animation error, and the communicator should have been in his whip. Been a while since I’ve last watched the episodes - although rest assured when I get time again, I shall investigate this new proposed order, and see if there’s anything wrong with it.
Thanks adesse!
Yes, Tygra used a hand communicator in “Mongor”, so I got confussed. But not at all… my confussion came because now I remember that when watching that scene in “Mongor”, I thought “but wasn’t there a comlink in their weapons now?”.
As yopu said, that was stated in “Time Capsule”, so if anything, “Mongor” should come before that episode, not after. I knew there was a time slip in “Mongor”, just didn’t remember how it was done 
It bugs me as well.
The only trouble is, if we say they had these handheld communicators first, before Panthro developed them in their weapons, then why bother developing them in the weapons at all? Moreover, how come they never appeared in any other episodes?
Mind you, the idea of putting “Mongor” before “The Time Capsule” is valid. Maybe those old hand-held communicators were giving out on them and Panthro developed something new into their weapons.
Now we just need to settle on an exact spot. I’ll just have a look . . .
HOUSTON WE HAVE A PROBLEM!
CLIP (Continuity Loop of Infinite Paradox):
“Mongor” must come before “The Time Capsule” because of the communicators, but “The Time Capsule” is the debut appearance also of the Kittens’ spaceboards, which are also seen as being established in “Mongor”.
In this instance, I think “The Time Capsule” should come first, and there are two ways we can do this:
I would tend to agree with number 1.
Actually, I’ve thought of a way that it can work without being an animation error:
In “Out Of Sight”, Tygra surmises that making himself and Nayda invisible must have overloaded the whip, and it takes the Sword of Omens to make them visible again - it’s entirely plausible that this could have damaged the communiator in it as well.
SO if we have “Mongor” right next after “Out Of Sight”, we can say Tygra’s making do with a spare communicator until Panthro finds the time to fix the communicator in his whip.
A little far-fetched, but fine by me lol
Okay, in accordance with Liam’s suggestion above, I’ve swapped Queen of Eight Legs and Mongor, in order to put Mongor immediately after Out of Sight. I think the only restriction on QEo8L is that it has to come before Excalibur, which is still the case. So now we have:
Well, that was fun! I assume we don’t have any quibbles with the standard season 2 order? 
I’ll give that new continuity order a go when I next get a chance to watch the DVDs. There may be the odd continuity point that we have overlooked. (For which reason, may I suggest to the moderators that this topic should be a sticky one, or whatever the term is.)
And may I also say, a big thanks to everyone who has helped with this, finding the answers where I had a blank, and reminding me of other little details.
AS FOR SEASON 2:
I’m not aware of any problems with the season 2 continuity - or if you prefer, the seasons 2-4 continuity - but if there are, obviously the 5-parters punctuate it precisely, so it’ll be in three sections of 15, much easier, there’s nothing from one of these seasons that belongs in another!
And indeed, not even that, because there’s at least one episode at the start and/or end of each of the individual 15s, i.e. “Cat Fight”, “The Circus Train”, “The Last Day”, “The Book Of Omens”, that are quite definitely fixed in continuity order.
WELL, I’ve just printed out a copy of this continuity order, might still be a little while before I get to try it out as I’m currently moving house (slowly!).
OK, I’ve just about completed viewing the episodes in this new order, and there are one or two issues:
Firstly, I would like to pick one tiny fault my original ordering of the early episodes:
“The Terror Of Hammerhand” and “The Tower Of Traps” should be switched round. That way, “The Tower Of Traps” is the first regular episode, and it has the Kittens mentioning Tygra wanting accurate maps of Third Earth, and that way having “The Terror Of Hammerhand” right AFTER instead of before better explains their absence from that one.
Secondly, there’s a few cases (not got them to hand right now) of “Y must follow X” being inserted into this continuity order as Y following on IMMEDIATELY from X, which just feels a bit clunky. For example:
“Dr Dometone” right after “Mandora And The Pirates”
“Mumm-Rana” and “Jackalman’s Rebellion” right after “The Transfer”.
There’s more, but I can’t remember offhand.
I just discovered this thread and I love it! So is there a definitive final list?
Not quite yet, we need to get the hive mind working on this again to fix a few bugs. But we’re getting there!
This is a very interesting list. It certainly helps to clear up many of the plotholes and continuity errors.
I’ve been following the order posted by fallen_one on the previous page (and pasted below). It’s been at least seven or more years since I’ve watched the series at all, and watching it without contradictions/continuity errors is making me a fan all over again. And I’m only up to Time Capsule (#14). So far I haven’t seen any instances where the new order causes any new discrepancies.
It was especially nice to have “Spitting Image” come before “The Ghost Warrior,” since at the end of “Spitting Image,” Cheetara says something like, “Who would’ve ever thought of a ThunderCat gone bad?” Her statement makes no sense if it comes after the intro of Grune (as it did in the original continuity). So, kudos to the listmakers!
Still enjoying watching it in this new continuity order. I’m up to “Mongor” now - episode #28. The only clunky thing I noticed was Vultureman’s out-of-the-blue first appearance, but I’m not sure that’s avoidable.
He never had a formal introduction in that sense, so you’re right. I figured the flashback in “Return To Thundera” was the best bet, and made sure he wasn’t seen on Third Earth until after both it and “The Fireballs Of Plun-Darr”, because he’s the group’s inventor, and was absent from both of those episodes that involved mutant inventions.
There’s one or two things I’d like to change about the current order we’ve got on here - mainly on the grounds that “Y must come after X” does not automatically mean “Y must come immediately after X”. Things like having “Dr Dometone” right after “Mandora And The Pirates”, I’d prefer the Mandora reference in the former to have a bit of distance from her actual appearances. Similarly “The Transfer”, “Mumm-Rana” and “Jackalman’s Rebellion” - the first of these should come before the other two, and indeed does in our list, but that list has them all back-to-back.
I understand what you mean, but I actually prefer it that way – having certain events fresh on the mind when a related event happens in the very next episode. I was actually bummed when Vultureman’s threat of revenge on the ThunderCats (I forget which episode… “Wolfrat,” maybe?) wasn’t followed up immediately by “The Super-Power Potion.”
Vultureman’s threat of revenge was in “Out Of Sight” - and actually, it makes a bit of sense that “The Super Power Potion” doesn’t follow it immediately, because if he’s working on a potion like that, it is going to take some time to get it right!
As for your general point, it depends on the events really. Sometimes they do need to follow immediately - putting “The Thunder Cutter” right after “Return To Thundera” makes Monkian’s comment in the former about the sword getting more powerful every day seem apt - and sometimes they don’t. If it’s just passing references, then there probably should be a gap.
I have been reading this thread with some interest guys. Very academic, I am impressed!
Have you guys consulted the production episode order (not the airdate, but the order in which the episodes were made by Rankin & Bass?
http://www.thundercatslair.org/animated-series/original-series/episode-guide/