Political experts have three major things to say about the final presidential debate: * Ronald Reagan needed only a ''draw'' to be satisfied. He apparently did at least that well.
* Walter Mondale needed a victory as decisive as the one in Louisville, Ky. He didn't get it.
* Mr. Reagan was far ahead in this campaign before the debate. He still is.
Analysts observe that the Kansas City debate was probably Mr. Mondale's last big opportunity to make this race close. Pollster G. Donald Ferree Jr., associate director of the Roper Center, says Mondale failed to make it work.
''The political impact of this final debate will most likely not be very great,'' Mr. Ferree concludes.
Even though Mondale had ''won'' the first debate, his task coming into Kansas City was very difficult.
The reason: Despite Mondale's recent gains in the polls, Mr. Reagan is holding steady at about 56 percent. David Chagall, publisher of Inside Campaigning, notes that the President's strength hasn't varied more than a point or so since August.
This means that all of Mondale's new strength is coming from voters who were undecided. And that isn't good enough for him.
With Reagan at well over 50 percent, Mondale must find a way to shake loose a large number of Reagan loyalists. He's having little or no success.
So is all hope lost for Mondale? His campaign chairman, James Johnson, insists that private polls show the race is closing in key states like New York and Pennsylvania. He says this final debate gave Mondale at least two major talking points that he will hammer home with the voters: problems with the Reagan ''star wars'' plan, and the President's ''lack of knowledge'' about his job.
In the so-called ''star wars'' issue, the President has supported a major research program by the Pentagon to find ways to defend the United States against an attack by nuclear missiles. Such a program, if successful, could render nuclear-tipped missiles ''obsolete,'' the President says.
Further, the President says he would share ''star wars'' technology with the Soviets, if that would make the world a safer place. The idea of sharing the foremost US defense technology with the Soviets is a ''naive notion,'' says Mr. Johnson. How can the US be expected, asks Johnson, to ''sit down with the Russians, give them our technology, show them a demonstration shot? (Would) that be with a nuclear weapon, or what?''
The whole Reagan strategy on ''star wars'' is absurd, Johnson argues. In the final two weeks, Mondale will also question whether Reagan is competent. He will ask whether Reagan has done his homework on arms control and nuclear weapons. To back this up, Johnson pulls from his pocket a copy of a May 1982 Reagan press conference. Johnson says the transcript proves the President didn't know submarine-launched nuclear missiles could not be recalled after being fired.
What are the facts? The record shows that during the press conference, the President spoke of the dangers of land-based nuclear missiles. Those missiles, he said, are the ''most destabilizing. ... That is the one that people know that once the button is pushed, there is no defense; there is no recall.''
The record shows that Mr. Reagan then continued: ''Those that are carried in bombers, those that are carried in ships of one kind or another, or submersibles , you are dealing there with a conventional type of weapon or instrument, and those instruments can be intercepted. They can be recalled if there has been a miscalculation. And so they don't have the same, I think, psychological effect that the presence of those other ones that, once launched, that's it; they're on their way, and there's no preventing, no stopping them.''
What did the President mean? Robert C. McFarlane, the White House national-security adviser, says Reagan was clearly ''referring to platforms,'' such as bombers or submarines, which can be sent toward a target and then recalled. But Johnson says the reference was to missiles, not platforms.
Whoever is right, analyst Horace Busby thinks Mondale will find no political firepower in the missile debate. Mr. Busby, a veteran of Lyndon B. Johnson's White House, says the whole charge against Reagan ''is pretty fraudulent.'' Mr. Ferree of the Roper Center suggests that no matter who may be right, the subject is a little too esoteric to generate much political excitement. Mr. Chagall also discounts the importance of the ''star wars'' and submarine missile issues; if Mondale pursues them, Reagan will probably pull even further ahead, he says.
What might have been an important issue - the President's age - was probably put to rest in this debate. After the President's halting performance in Louisville on Oct. 7, the big-three TV networks, major newspapers, and magazines all revived charges that Reagan is too old.
But as Sen. Paul Laxalt (R) of Nevada, a Reagan ally, had promised, it was ''a new Reagan'' who appeared here in Kansas City. His answers were quicker, his humor sharper, his language more crisp. As he often does, he deflected potential trouble with a quip. When asked about his age, he responded:
''I will not make age an issue in this campaign. I am not going to exploit, for political purposes, my opponent's youth and inexperience.''
Early polls gave a slight edge in the debate to Reagan. ABC-TV showed Reagan winning 39 to 36 percent, with 25 percent undecided. Gallup-Newsweek had 43 to 40 for Reagan, with 14 percent undecided. USA Today had 44 to 27 for Reagan, with 21 percent saying it was a tie and 8 percent undecided.