In keeping with the “what do all those words in the credits mean, anyway?” theme, I was watching a show the other day and noticed a 2nd Unit Director was credited, and started having flashbacks. Then I wondered how many people know what a 2nd unit is. So I shall tell you!
A 2nd unit is, plainly, when you have a whole separate crew shooting scenes for your show.
Done! Or, err…. not. Because there can be a lot of different kinds of 2nd unit, depending on why you need one. If one episode needs to shoot a little long, they may overlap their schedule with the next episode and then you need two units because two episodes are shooting at the same time. Or if the post production team has realized that they need a lot of insert shots (quick shots of, for instance, a hand opening an envelope or glasses clinking together in a toast) for a lot of different episodes, they may put together their own second unit. They usually won’t use the regular actors (a hand is a hand is a hand, right?) so they’ll get people from the production office or whoever’s around to do it. (I usually managed to bow out of these because I have surgery scars on my hand.)
Sometimes a show will use a second unit because they just have so much to shoot, or so many overnight scenes, but the guilds all have turnaround rules (they mandate how much time their workers get between shifts so everyone has time to go home and sleep) so the only way to make it work is to bring in a second crew. Some shows, like Heroes, were notorious for always having a 2nd unit, since they were so stunt-heavy and their characters tended to have isolated plotlines, so they could get away with it with the actors. (No matter how many crews you have, you cannot duplicate your actors or have them in more than one place at a time.) On a commentary track, Joss Whedon says Buffy started shooting with a 2nd unit after the second time a PA fell asleep at the wheel on their way home.
As someone who once worked in the production office, 2nd unit is almost always code for “hell.” You’ve got a whole crew that doesn’t know how your show works, you’ve got twice the call sheets and production reports, twice the locations, possibly twice the meals and likely many more hours in the day. Which, yes, overtime is nice but when your regular day is 12 hours, overtime can lose some of its charm. But it is one of the tools at the disposal of TV production, and they don’t use it lightly.