There was only one mention of two Minbari castes - it came in "Grail" and the speaker was Lennier. Now as it happens JMS replied to a message on the web at just around the time "Grail" was filming in which he states that there are
three Minbari castes and names them. So I don't think this is an error or that he "added" the third caste later.
"Grail" originally aired in the U.S. in July 1994. It was production number 109 and would have shot around December of 1993.
From: STRACZYNSKI [Joe]
Subject: Yeah, fairly much, as far as it...
To: GENIE
Date: 12/25/1993 7:28:00 PM
No Thread
Yeah, fairly much, as far as it goes. There's some Jananese influence, as well as some early European influences, as well as middle Eastern influences. (There are three Minbari castes: the worker, warrior and religious castes.)
jms
Here's another from April 1994, 4 months
before "Grail" aired, in which JMS casually refers to a "worker class" Minbari, indicating that their existance was known to the on-line community well in advance of the episode:
From: STRACZYNSKI [Joe]
Subject: Lennier is not in the cargo area...
To: GENIE
Date: 4/24/1994 7:47:00 PM
No Thread
Lennier is not in the cargo area during the beating, nor is he in BG during the negotiations. That's a Minbari of the worker class. (You can generally tell from the orange-ish smock-thingie they wear.) Sorry.
jms
That post refers to "Deathwalker", which had just aired in the U.S. It was shot as episode 113. JMS comment would seem to indicate that they had
already established a different wardrobe for Worker Caste Minbari by that point, and that it had been used in previous episodes.
Clearly JMS had already conceivd the Worker Caste in season one, even if it remains technically possible that he invented them the day
after "Grail" finished shooting.
I think Lennier omits the Workers because they either don't figure much in his thinking (the typical attitude of the Religious and Warriors which he is much more likely to need to outgrow than Delenn) or he knows that outsiders like Aldus are unlkely to have contact with them. (He is contrasting the level of cooperation the Religious caste will give Aldus's quest with that of the Warriors, so he may simply have been focused on who Aldous be speaking to, not cluttered up the discussion with details of Minbari culture that had nothing to do with Aldus's mission.) Delenn doesn't correct him (or at least doesn't do so in front of their guest) because to do so would cause Lennier to lose face and the point is a minor one. (As Delenn says with regard to concealing Aldus's request from the Warrior caste, "So we will not tell them, and spare them the confusion." That could equally apply to her not teling Aldus about the Worker caste.
BTW, although I agree that
In the Beginning contradicts "Points of Departure", I don't think this is an error. JMS conciously decided to violate continuity because when it came time to depict the incident on-screen in the context of the TV movie - rather than in a passing reference in dialogue - it made more dramatic sense to do it that way. The same way Zathras's appearance in "War Without End" contradicts what was stated in "Babylon Squared" - for production reasons there wasn't the time or the money to shoot what the earlier episode called for, so JMS just fudged the whole thing and kept on going, trusting to the pace of the episode to carry the audience past the hiccup. But neither is technically an
error, which is an accidental mistake like losing Delenn's original gown and having the sleeves mismatch, or Sheridan putting Jack the Ripper in the wrong end of London.
Regards,
Joe