Thomas mentions Goodnight. He is talking about Charles Goodnight, who Woodrow F Call represented in Lonesome Dove. Lonesome Dove was a big influence on this series.
Elsa said in less than 3 weeks they had shrunk by half. Eight men, six women, and four children had died. She then goes to mention that they were leaving at least that many behind. 8+6+4= 18. 18x2=36. 36x2 = 72. 72 is approximately the total number of people that they started out with all together.