This episode takes place in September of 1869.

Coop: A shawl? A little girl in the desert in August? You must be losin' your mind, Charlie.

Hale: Funny thing about liars, Charlie, they believe their own lies.

Coop: (to Hawks about Wooster) You know spring comes a little later each year at his time of life.

Coop: The only experience I've ever had with spirits is the mornin' after when I wake up with two heads.

Barnaby: Do you believe in ghosts?
Hale: I never saw one but I never saw Niagara Falls either. I'd be stupid to deny they exist because of that.

Hawks: Say Barney, you fixin' something special for breakfast?
Barnaby: Yeah, poison ivy salad. It's even tastier than my stew.

There really was a Donner Party as mentioned in the dialogue. Most of the party perished due to inclement weather and starvation while on their way to California in the 1840's. Some of the survivors are reported to have resorted to cannibalism in order to survive.

Kind of an eerie episode that deals with the supernatural, a topic that few Westerns tackled. All that's missing for Little Girl Lost to be an episode of The Twilight Zone is Rod Serling's opening and closing narration.