User blog comment:Western Gen/Speculations for Season 12/@comment-198.45.201.206-20140517141734/@comment-173.58.251.107-20140517204915

They were, Shannon McCormick, Matt Hullum, and Dan Godwin's names were listed in the trailer's credits. This doesn't mean they'll be guaranteed to appear in the season itself, they could be playing random grunts or something like that, but the fact their names are present indicate that there is a chance that Wash, Sarge and Donut will appear.