The moment Donald Trump shot himself in the foot at the Republican debate

At this point in the campaign, Republican debate moderators should have a healthy understanding that they're one exchange away from being dragged into the debate themselves. (See: Kelly, Megyn)

Candidates at Wednesday's CNBC debate in Boulder, Colorado, seemed extra anxious to go after their questioners — so much so that clashing with the moderators became a major theme of the debate.

Debate watchers on social media rightly criticized CNBC's moderators for their questions and for not being able to rein in candidates when they went out of bounds, either on time or substance. But, at times, the 2016 hopefuls on stage seemed to pounce on the moderators with little reason or disputed some facts that weren't exactly in their favor.

The arguments were often left unsolved as the moderators tried their best to, well, moderate and keep the debate moving on.

Here are five instances of candidates sparring with the moderators, along with (hopefully) some clarity.

A candidate-vs.-fact moment came when moderator Becky Quick asked Trump why his immigration plan criticizes Facebook CEO Mark Zuckerberg, calling him Marco Rubio's "personal senator."

Trump responded with a classic politician denial: "I never said that." Quick apologized.

Except that Trump did say that. As The Washington Post's Max Ehrenfreund points out, a screen shot from Trump's campaign Web site reveals his white paper on immigration is critical about the controversial program to allow visas for skilled immigrants, known as H-1B. It also criticizes Zuckerberg's stance on the visa program. And it includes the "personal senator" language.

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Trump's apparent contradictions didn't stop there. Ehrenfreund notes Trump appeared to praise the program, despite what his Web site says.

"I am all in favor of keeping these talented people here, so they can go to work in Silicon Valley," he said.

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One of the first moderator/candidate showdowns of the night came when CNBC moderator Carl Quintanilla asked Ben Carson about his decade-long relationship with Mannatech, a nutritional supplement company that made dubious (and litigated) health claims.

Carson denied his involvement, explaining away his photo on the company's Web site as "total propaganda." Oh yeah, and he did a few speeches for them and takes the product (which he endorsed on-stage). But that's it.

Quintanilla pressed him. "Does that not speak to your vetting process or judgment?"

At this point, the audience jumped to the soft-spoken Carson's rescue, booing Quintanilla loudly.

"See?" Carson said. "They know."

The follow-up wasn't a great moment for Quintanilla. He might have been better focused on the substance of Carson's connections to the company, which are much more complicated than Carson let on.

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When it was Texas Senator Ted Cruz's turn to answer a direct question — about the debt ceiling — he first had some grievances to air about the debate itself. Cruz felt the moderators were too busy pitting the candidates against one another and talking about the horse race rather than asking questions about serious policy.

"The men and women on this stage have more ideas, more experience, more common sense than any participant in the Democratic debate," Cruz said.

It was, as The Washington Post's David Fahrenthold and Abby Phillip note, one of the most reliable attack lines in a candidate's debate portfolio: Attack the moderators for asking the wrong questions. And it definitely got Cruz big applause.

The problem? Cruz left no time in his takedown of the debate's apparent lack of substance to actually comment on a question that was, well, substantive.

Quintanilla noted that Cruz had not answered that question about the debt ceiling, but Cruz continued to attack the moderators. By the end of the exchange, his time was up, and he was not allotted more time to answer the specific question.

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Time for a drill-down into Rubio's tax plan. Moderator John Harwood wanted to know why the nonpartisan Tax Foundation found Rubio's tax plan gives more after-tax gains to the top 1 percent than to middle-class Americans.

"Since you're the champion of people living paycheck-to-paycheck, don't you have that backward?" Harwood asked.

Rubio flatly insisted Harwood was wrong.

"You wrote a story on it, and you had to go back and correct it," Rubio said.

It was Harwood's turn to offer a stern denial: "No, I did not."

The situation quickly devolved into a he-said, he-said, with the audience applauding, apparently taking Rubio's side.

According to Politico, here's what happened:

Harwood posted a tweet two weeks ago acknowledging an error in his comparison of how the richest and poorest would fare. That tweet circulated again during the debate, with calls from frustrated conservatives demanding that he correct the error on air. But on air, Harwood accurately compared benefits for the richest and middle classes -- it was Rubio who chose to compare how the richest and poorest would do.

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Toward the end of the debate, it seemed like a blow-up at a moderator could happen at any given moment, like when New Jersey Governor Chris Christie was asked to explain his proposals on climate change.

As candidates are wont to do, Christie started off with generalities. Harwood pressed him for specifics. Christie, who was already in attack mode after complaining about fantasy sports being a debate issue, went off on Harwood.

"Do you want me to answer or do you want me to answer?" Christie said. "Even in New Jersey, what you're doing is rude."

But if you look at the transcript, Christie seemed to be reverting to talking points and criticizing Democrats. Harwood was trying to get beyond that.

Here's the exchange. You can judge for yourself:

HARWOOD: Governor Christie, you've said something that many in your party do not believe, which is that climate change is undeniable, that human activity contributes to it, and you said, quote: "The question is, what do we do to deal with it?".

So what do we do?

CHRISTIE: Well, first off, what we don't do is do what Hillary Clinton and John Kerry and Barack Obama want us to do, which is their solution for everything, put more taxes on it, give more money to Washington, D.C., and then they will fix it.

Well, there is no evidence that they can fix anything in Washington, D.C.

HARWOOD: What should we do?

CHRISTIE: What we should do is to be investing in all types of energy, John, all types of energy. I've laid out...

HARWOOD: You mean government?

CHRISTIE: No, John. John, do you want me to answer or do you want to answer?

(LAUGHTER)

How are we going to do this?

(APPLAUSE)

Because, I've got to tell you the truth, even in New Jersey what you're doing is called rude. So...

(LAUGHTER)

We've laid out a national energy plan that says that we should invest in all types of energy. I will tell you, you could win a bet at a bar tonight, since we're talking about fantasy football, if you ask who the top three states in America are that produce solar energy: California and Arizona are easy, but number three is New Jersey.

Why? Because we work with the private sector to make solar energy affordable and available to businesses and individuals in our state.

We need to make sure that we do everything across all kinds of energy: natural gas, oil, absolutely. But also where it's affordable, solar, wind in Iowa has become very affordable and it makes sense.

That is the way we deal with global warming, climate change, or any of those problems, not through government intervention, not through government taxes, and for God's sake, don't send Washington another dime until they stop wasting the money they're already sending there.

HARWOOD: Thank you, Governor.