A "clip show" is an episode of a series that essentially takes a look back at what they've already done. It's a pretty popular trope, since it saves the production a whole bunch of money, since they're looking back on old stuff, and not having to shoot new stuff.
本季《邪恶力量》有非常关键的一集名叫《Clip Show》,这一集我们将会闪回过去。闪回真心是现在电视剧非常喜欢使用的一种省钱制作手法,因为剧组可以直接找以前出演过的演员,不用再找新演员试镜。

Guest stars Taylor Cole, Graham Wardle, and Cindy Busby, from previous seasons, will all be returning. Fans, of course, remember Cole as Sarah Blake from "Provenance." She was one of Sam's more likeable love interests over the course of the series.
之前曾客串过的演员Taylor Cole、Graham Wardle和Cindy Busby都将会在这一集回归。大家应该都还记得Cole扮演的Sarah Blake吧。她可以算是Sam在这部剧中人气比较高的女友了。

Wardle was in the second episode of the first season, as a kid who was nabbed out of his tent by a creepy, people-eating Wendigo. Luckily, Sam and Dean saved him and returned him to his sister safely.
Wardle曾经在《邪恶力量》第一季第二集中出现过,他扮演一个被怪物(Wendigo)从帐篷里抓走的孩子,还好最后被Sam和Dean救了回来。