One other episode I can think of is during the 1967 Laura story which has a scene set in Phoenix, Arizona.  I remember it featured Dr. Guthrie, Frank Garner, and the two Phoenix policemen.  Not sure who else is in it.

Another unusual 1897 episode has no women in it.

Interesting trivia on John Beal, who plays Judge Vail.  In 1964 he was hired to play lead character Jim Matthews on Another World and was fired after the first episode.

It would be interesting to see if there is a video of that episode somewhere and see what caused that to happen so suddenly.

He turned 90 yesterday, the age his character Ezra Braithwaite was.

Quentin & Daphne were moving to Boston with Tad weren't they? I have to check the 1840 Concordance.
Desmond & Letitica were moving to New York.

I find that I don't care for Edith or Gabriel, as they don't factor into the main plot and are obviously "shoehorned" in, which given the outcome was futile anyway.  They were better off staying in the background.  Edith fooling around with Gerard was too much for me.  There should be at least some grounded characters in the family.

IMHO...The 1840 bunch aren't anywhere likeable as the 1897 family were.  There's too much needless drama.

Has Edith anything but spite in her?  I can't believe she ever had any use for Gabriel, so she must have married him for the life of luxury at Collinwood, so she shouldn't be complaining about it now.

Is it possible that this is another parallel time 1840?

When David & Amy went exploring the west wing, they came upon a portrait of a Thaddeus Collins, who David said was alive during the Civil War.

This couldn't be 1840 Tad as he died in 1840 in the original timeline.

I am thinking that perhaps the actions of Gabriel & Edith were manipulated by Judah Zachary to rid himself of the rest of the Collins family to coincide with Quientin's hanging.

[spoiler] Edith may have been unconscious after her strangulation, appearing that she was dead at the time to Gabriel.  As for Gabriel, he may have also ended up unconscious falling down the stairs, only this time he legs really became paralyzed.  He dies in 1863 as Edith said in 1897.  

As was stated in a previous post, this may have led to the both of them being reformed.  
[/spoiler]

The writers really should have had Edith & her husband (not Gabriel) on vacation or something so they couldn't mess things up.  Terry Crawford could have played another Collins wife married to Gabriel.

As Dan Curtis was a penny pincher, I'm surprised  he never considered casting himself on DS as an extra or a one/two episode character.   Would this have been against the rules of the actors union?

Imagine DC as Dr. Fisher, King Johnny Romano, etc.