By Thursday morning, Mr. Fletcher’s videos were the talk of the Republican internet. “Why is it taking regular Americans to expose this level of obvious corruption?” said Candace Owens, a conservative commentator, sharing one of the videos to her 2.7 million Twitter followers.

Yet a few phone calls by Mr. Fletcher would have revealed evidence that indicates that what appeared to be fraud were run-of-the-mill clerical errors.

In one case, a 74-year-old woman in Hamlin Township, Mich., had asked for an absentee ballot for the first time in years, setting off a notice from the state’s digital voter rolls that her birth date was not on file, according to Catherine Lewis, the town’s clerk. The system had assigned the woman the default birth date: 01/01/01, or Jan. 1, 1901.

Ms. Lewis said she knew the woman. Hamlin Township, a rural community on Lake Michigan, has just 3,400 people. She said she had driven to the woman’s home and collected a copy of her driver’s license so she could vote by mail. But Ms. Lewis had not gotten around to updating her file. “Rest assured,” Ms. Lewis said, “she is a legal voter.”