Six Strangers at Apache Springs - S2-E7
Continuity mistake: In memory of their friend Seth, who died in "Smiler with a Gun," Curry grew a mustache that he kept for several months. (As a running joke, Heyes kept prodding him to get rid of it and Curry kept refusing.) Because production and air dates differed, the mustache is, without explanation, missing here. It's back in the next episode, gone again in the next, and reappears for the last time in the next, where Curry finally shaves it off.