The cast for the week is listed in the end credits. The main players are also listed in the title sequence; but on IMDb longer credits trump shorter credits, and so the actors are listed according to the end credits. Rick Hearst (as Whip Jones) appears in the title sequence, but not the end credits; and so his credit appears last on IMDb's list.
As always, some actors (including Hearst) are credited who don't appear in the present episode. These actors are listed on IMDb as credit only. Any actor who appears but isn't credited is listed as uncredited.