Former President Donald J. Trump capped off the week of his first, and possibly only, presidential debate against Vice President Kamala Harris with an unfocused speech at a rally in Las Vegas on Friday night, where he baselessly accused her of cheating, repeated a number of falsehoods on a wide range of topics and continued to try to stoke fear about immigration.

Over the course of an hour and 20 minutes, Mr. Trump ranted about the moderators of Tuesday’s debate, made unfounded accusations that Democrats “cheat like hell” in elections and insisted that President Biden, whom he spent years attacking as a weak president, “would have been better than” Ms. Harris.

And even as Mr. Trump continued to insist that he had been victorious in the debate — though some of his allies have acknowledged he had a rough outing — he accused Ms. Harris of wearing an earpiece in their matchup, a baseless claim that has proliferated on right-wing social media. And he said that Ms. Harris had obtained the questions in advance, an assertion for which there has been no proof.

Mr. Trump insulted his Democratic opponents, calling Ms. Harris “Kambabla,” a mispronunciation of her given name, and he called her running mate, Gov. Tim Walz of Minnesota, “the vice president,” as he did in a speech on Thursday.

And in a bid to characterize Ms. Harris and Mr. Walz as overly liberal, he repeated false claims that he has frequently made since Ms. Harris became the Democratic nominee. Mr. Trump said Ms. Harris supported states’ taking minors from their parents to perform gender-affirming surgeries on them. No state allows such surgeries to be performed without parental consent.

And Mr. Trump once again insisted that Democrat-led states allow babies to be executed after birth. Infanticide is illegal everywhere in the country.