It gave a prohibited political gift to help Florida Attorney-General Pamela Bondi. It appears to have bought items for Trump - including a US$12,000 football helmet and a US$20,000 portrait of Trump - despite IRS rules against "self-dealing" by charity leaders.
And, in at least five cases, the Trump Foundation may have reported making a donation that didn't seem to exist.
These five cases turned up in the Post's reporting, which looked at 24 years of tax filings and contacted more than 200 people and groups listed in those filings as donors or recipients of gifts.
Five times, the Trump Foundation's tax filings described giving a specific amount of money to a specific charity - in some cases, even including the recipient's address. But when the Post called, the charities listed said the tax filings appeared wrong. They'd never received anything from Trump or his foundation.
The Post asked Trump's staff to explain these five apparent errors.
It has explained one.
Regarding that one (No. 5 on the list below), the Trump organisation's explanation showed something very unusual. The incorrect gift had been listed on the Trump Foundation's tax filings in a way that served to hide a real gift - the improper donation to Bondi's group - from the IRS. Trump's staffers say there was no intent to mislead: The improper gift was left off, and the false gift was added, by accident.
It's still unclear how the four other apparent errors arose.
We post them here, in case somebody out there knows more of the story than we do.
INCORRECT LISTINGS
1 A US$10,000 gift to the Giving Back Fund in 2008.
The Giving Back Fund is a Los Angeles-based charity that serves as an umbrella group for smaller charities run by actors and celebrities. Marc Pollick, the group's president and founder, said the group had searched its donor files and found no evidence of this gift. "We have already reached out to the Trump Foundation to ask them to actually SEND us the US$10,000 that they claimed they sent in 2008!" he wrote in an email.
Trump's campaign did not respond to a request for an explanation of this gift.
The Trump Foundation's accountants - the firm WeiserMazars - declined to comment about this gift, and all the others, citing company policy.
2 A US$5000 gift to the Children's Medical Centre in Omaha, Nebraska, in 2010.
"Children's Hospital & Medical Centre's Foundation does not have a gift from the Donald J. Trump Foundation or Donald Trump in its records," said Sarah Weller, a spokeswoman for the medical centre.
Weller suggested that the Trump Foundation may have sent the money to another children's hospital, in another city. But the foundation's tax returns had the right address for the one in Omaha, down to the suite number.
Trump's campaign did not respond to a request for an explanation of this gift.
3 A US$10,000 gift to the Latino Commission on Aids in 2012.
This was one of the gifts that Trump promised on air during a taping of The Celebrity Apprentice. During an episode in 2012, contestant Dayana Mendoza - a former Miss Universe - was there when Trump made a sweeping promise. "I'm gonna give US$10,000 each to each one of you, everybody sitting at this table, for your charity," he said.
Five other contestants were at the table. The Trump Foundation sent US$10,000 to each of their charities. This was typical for the show: Although Trump often made seemingly heartfelt promises to donate his own money, it seems that he never did so. Instead, the donations were made by a production company, or by Trump's foundation - by then, filled with other people's money.
The Trump Foundation told the IRS that it also had given US$10,000 to Mendoza's charity, the Latino Commission on Aids.
But the money didn't arrive. "No ... donations of any kind from Donald Trump or the Donald J. Trump Foundation were received," said Daniel Leyva, at the commission.
Trump's campaign did not respond to a request for an explanation of this gift.
4 A US$1000 gift to Friends of Veterans in 2013.
This January, the phone rang at a tiny charity in White River Junction, Vermont, called Friends of Veterans. This was just after Trump had held a televised fundraiser for veterans in Iowa, raising more than US$5 million.
Trump's campaign did not respond to a request for an explanation of this gift.
5 A US$25,000 gift to Justice for All in 2013
Justice for All is a nonprofit group in Kansas that seeks to "make abortion unthinkable" by training opponents of abortion to change minds about the issue.
"Our organisation, Justice for All Inc., did not receive a US$25,000 donation from the Donald J. Trump Foundation in 2013," staffer Tammy Cook told the Post earlier this year.
This is the one incorrect listing that Trump's organisation has explained.
First, Trump officials said, when the request came down to cut a check to the Bondi group, a Trump Organisation clerk followed internal protocol and consulted a book with the names of known charities.
