By Bill O'Reilly

There were three central themes Tuesday night in Las Vegas. No. 1, Mitt Romney and Rick Perry don't like each other. No. 2, all the Republican candidates don't like Herman Cain's 999 tax plan. And no. 3, Anderson Cooper lost control at a key moment in the debate. Let's take them one by one.

You may remember that Gov. Rick Perry lost some support when he told Americans that he opposes a border fence with Mexico and supports paying in-state college tuition for illegal aliens. Mr. Perry knows that hurt him, so Tuesday night he tried to turn things around by going after Mitt Romney on the illegal immigrant issue.

(BEGIN VIDEO CLIP)

RICK PERRY, GOP PRESIDENTIAL CANDIDATE: Mitt, you lose all of your standing from my perspective because you hired illegals in your home and you knew about it for a year. And the idea that you stand here before us and talk about that you're strong on immigration is on its face the height of hypocrisy.

ANDERSON COOPER, CNN ANCHOR: Gov. Romney?

MITT ROMNEY, GOP PRESIDENTIAL CANDIDATE: Rick, I don't think I have ever hired an illegal in my life and so I'm afraid -- I'm looking forward to finding your facts on that because that just doesn't…

PERRY: I'll tell you what the facts are.

ROMNEY: Rick, again, Rick.

PERRY: You had the -– your newspaper, the newspaper.

ROMNEY: I'm speaking. I'm speaking, I'm speaking. You get 30 seconds. This is the way the rules work here. I get 60 seconds.

PERRY: Well, no but the American people want the truth.

ROMNEY: And then you get 30 seconds to respond, right? Anderson.

(END VIDEO CLIP)

Before things got to that point, CNN's Anderson Cooper, the moderator, should have stepped in and allowed Romney to respond to Perry without interruption.

Now, I understand that bickering is good television, but in a presidential debate there has to be a central authority or noise wins. It's not like a cable news program where sometimes you have to let the guests fly.

Perry accused Romney of hypocrisy. Cooper should have provided Romney a moment to respond without chaos. When Romney finally did respond, he said this.

(BEGIN VIDEO CLIP)

ROMNEY: It's been a tough couple of debates for Rick, and I understand that, and so you're going to get -- you're going to get testy.

You wrote an op-ed in the newspaper saying you're open to amnesty, that's no. 1. No. 2, we hired a lawn -- a lawn company to mow our lawn, and they had illegal immigrants that were working there. And when that was pointed out to us, we let them go, and we went to them and said…

PERRY: A year later?

ROMNEY: You have a problem with allowing someone to finish speaking. And I suggest that if you want to become president of the United States you've got to let both people speak so, first, let me speak.

(END VIDEO CLIP)

The facts are these. After learning that his lawn mowing company in Massachusetts was using illegal labor, Gov. Romney told them not to hire illegals. They agreed, so he kept them on. Then they hired illegals again, so he fired them. The whole thing played out over a year. The Boston Globe broke the story. You can decide whether the issue has any relevance.

Next up in the barrel is Herman Cain, who was pounded over his 999 tax proposal.

(BEGIN VIDEO CLIP)

PERRY: Go to New Hampshire where they don't have a sales tax, and you're fixing to give them one. They are not interested in 999. What they are interested in is flatter and fair.

MICHELE BACHMANN, GOP PRESIDENTIAL CANDIDATE: If we give Congress a nine percent sales tax, how long will it take a liberal president and a liberal Congress to run that up to maybe 90 percent? Who knows?

RICK SANTORUM, GOP PRESIDENTIAL CANDIDATE: The fact of the matter is, I mean, reports are now out that 84 percent of Americans would pay more taxes under his plan.

RON PAUL, GOP PRESIDENTIAL CANDIDATE: The worst part about it is it's regressive. A lot of people aren't paying any taxes, and I like that. I don't think that we should even things up by raising taxes. So it is a regressive tax. So it's very, very dangerous.

ROMNEY: Will the people of Nevada not have to pay Nevada sales tax and in addition pay the nine percent tax?

(END VIDEO CLIP)

They would. The feds can't dictate what the states charge in sales tax, so the two have to be added together. For example, here in New York City the combined sales tax would be nearly 18 percent; even more on gas and other fuel.

As for low-income folks, they would indeed pay a bit more. Before it was cut, the Social Security payroll tax was 6.2 percent. Cain would knock that out completely, along with the 1.5 percent Medicare tax. So low-income folks would pay about 1.3 percent more to the feds if the 9 percent individual flat tax was passed into law because that would be on everybody.

Also, a 9 percent sales tax would hurt things like the fast food industry, clothing and non-essential items. Maybe the lower income tax rate would mitigate that, but in a weak economy 999 would be a gamble.

However, Herman Cain is all-in.

(BEGIN VIDEO CLIP)

HERMAN CAIN, GOP PRESIDENTIAL CANDIDATE: It is a jobs plan. It is revenue neutral. It does not raise taxes on those that are making the least. All of those are simply not true. The reason that my plan -- the reason that our plan is being attacked so much is because lobbyists, accountants, politicians, they don't want to throw out the current tax code and put in something that's simple and fair. They want to continue to be able to manipulate the American people with a 10 million word mess. Unfortunately, none of my distinguished colleagues who have attacked me up here tonight understand the plan.

(END VIDEO CLIP)

"Talking Points" understands it and wants the tax code revised, but 999 can be improved upon. It is a good start however.

For the record, Cain would also knock out most tax deductions, leaving in only charitable contributions. The 18.4 percent federal gasoline tax would also be kept by Cain, along with taxes on booze, tobacco, guns, phone service and some other stuff. As always, you can decide the worthiness of Cain's plan.

The debate Tuesday night was the liveliest yet -- a good thing -- and marks Rick Perry's return to the fray. The Texas governor took a bold, fresh approach, and it will be interesting to see if the folks will respond to it in a positive or negative way. The polls should provide an indication later this week.

Mitt Romney maintained his status as the guy to beat, taking the heat and dishing back.

Herman Cain lost some momentum, but that's to be expected. The guy was on fire for two weeks. Nobody could maintain that.

The other candidates are the other candidates. We respect them, but they are long-shots with the primaries closing in.

In order to compete in the presidential arena the candidates need big money, and that flows only to those who are perceived to have a good chance to win the nomination. Money, not lack of spirit, will narrow down the contest.

And that's "The Memo."

Pinheads & Patriots

Four-year-old Cole, who lives on Long Island, received some bad news recently.

(BEGIN VIDEO CLIP)

HERMAN CAIN, GOP PRESIDENTIAL CANDIDATE: So it will replace the corporate income tax, the personal income tax, the capital gains tax.

UNIDENTIFIED MALE: Cole, we have to watch this Republican debate. We have to watch it.

COLE: No!

UNIDENTIFIED MALE: We have to. It's important.

COLE: No!

(END VIDEO CLIP)

Can a 4-year-old be a pinhead? Yes, but in this case, not necessarily. You make the call on little Cole.

— You can catch Bill O'Reilly's "Talking Points Memo" and "Pinheads & Patriots" weeknights at 8 and 11 p.m. ET on the Fox News Channel and any time on foxnews.com/oreilly. Send your comments to: oreilly@foxnews.com.