Watch CNN GOP Las Vegas Debate in 100 Seconds

So what happened? The candidates tried to get real. There were moments of snapping at one another and a lot of jumping in by moderator Anderson Cooper. Herman Cain, who was expected to be the main target heading into the night, mostly fell out of the spotlight after a long argument about his now famous 9-9-9 tax plan.

The debate set the stage for the next round of campaigning. If you missed it, here it is shrunk down to a convenient 5-point lesson plan.

1. Hit the panic button!

Everyone not named Mitt Romney needs to get their name back into the conversation fast or they risk falling out of the race. As a result, there was a palpable sense of panic among the second-tier candidates as they ignored moderator Anderson Cooper and shouted attacks over each other at a dizzying pace. Rick Santorum, maybe the only candidate on stage to never have a real “surge” in the polls, exemplified this dynamic: at one point he drew boos from the audience for repeatedly drowning out Mitt Romney’s answer on health care.

2. Mitt Romney finally makes a (potentially big) gaffe

Romney’s been unflappable up until now and he turned in a mostly solid performance on Tuesday. But he also showed for the first time that he can be forced off his game with enough pressure. Under attack from Perry over reports that he used a landscaping service that employed undocumented workers, Romney let slip a phrase that will likely come back to haunt him. “We went to the company and we said, look, you can’t have any illegals working on our property,” Romney said. “I’m running for office, for Pete’s sake, we can’t have illegals.”

Watch the moment: