The second season added the line "47,875 survivors in search of a home called Earth" in the opening sequence starting with Episode #2.1 "Scattered" and decremented it in every subsequent episode based on how many characters were killed off in the previous episode (or occasionally, as when the Pegasus returned, increasing it when the population increases).
Scattered: 47,875 Valley of Darkness: 47,874 Fragged: 47,862 Resistance: 47,861 The Farm: 47,857 Home (Part 1): 47,858 Home (Part 2): 47,855 Final Cut: 47,853 Flight of The Phoenix: 47,853 Pegasus: 49,605 Resurrection Ship (Part 1): 49,604 Resurrection Ship (Part 2): 49,604 Epiphanies: 49,598 Black Market: 49,597 Scar: 49,593 Sacrifice: 49,590 The Captain's Hand: 49,584 Downloaded: 49,579 Lay Down Your Burdens (Part 1): 49,579 Lay Down Your Burdens (Part 2): 49,550 Survivors after Lay Down Your Burdens (Part 2): 39,192
At the end of the closing credits, there is a different, short cartoon skit of the two producers, Ronald Moore and David Eick, which usually ends with one causing the death of the other in some imaginative way.
The second half of the opening credits for the first season is a montage of quick teaser clips from the current week's episode. Ron D. Moore said he took the idea from "Space: 1999". This was removed at the beginning of the second season, but later reinstated.
Opening title cards read for the second season: "The cylons were created by man. They evolved. They rebelled. There are many copies. And they have a plan."
Opening title cards read for the first season: "The Cylons Were Created by Man. They Rebelled. They Evolved. They Look and Feel Human. Some are programmed to think they are Human. There are many copies. And they have a Plan."